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Design Build Program Learn Compete 






9 




FOR THE ROBOT INNOVATOR 

www.servomagazme.com 



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ERVO 



10.2012 



VOL. 10 NO. 10 



MAGAZINE 




Columns 

08 Robytes 



byJeffEckert 
Stimulating Robot Tidbits 

10 GeerHead 

by David Geer 
Collaborating With Hubo 

14 Ask Mr. Roboto 

by Dennis Clark 

Your Problems Solved Here 

74 Then and Now 

by Tom Carroll 

The Many Ways to Control 

a Robot 



Departments 



The Combat Zone... 

32 BUILD REPORT: 

Testing the Prototype: Klazo - 
My 1 lb Drumbot From 
Kitbots.com 

Upcoming Events 

Clash of the Bots 3 

The History of Robot Combat: 
Robot Battles at Dragon*Con 



06 


Mind/Iron 


20 


Events 




Calendar 


21 


Showcase 


22 


New Products 


26 


Bots in Brief 


66 


SERVO 




Webstore 


00 


Robo-Links 


00 


Advertiser's 




Index 




PAGE 20 



SERVO Magazine (ISSN I546-0592/CDN Pub Agree#40702530) is published monthly for $24.95 per year byT & L Publications, Inc., 430 Princeland Court, Corona, CA 92879. 
PERIODICALS POSTAGE PAID AT CORONA, CA AND AT ADDITIONAL ENTRY MAILING OFFICES. POSTMASTER: Send address changes to SERVO Magazine, P.O. Box 
I S277, North Hollywood, CA 9 1 6 1 5 or Station A, P.O. Box 54, Windsor ON N9A 6|5 ; cpcreturns@servomagazine.com 

4 SERVO 10.2012 



In This Issue 







42 Give Yourself a Wedgie! 

by Zachary Lytle 

A wedge robot is a simple and durable design, 
and is the perfect platform for your first bot. 
Follow these construction details to build 
one for yourself. 

50 Finding NEM010 

by Fred Eady 

Every microcontroller that exists can be 
instructed to produce an RS-232 data stream. 
However, a microcontroller may not be robust 
enough to handle a TCP/IP stack. If your robotic 
device can speak RS-232, the NEMO10 can be 
used to translate the resultant RS-232 data 
stream into a TCP/IP packet. 



58 Troubleshooting 
Tips and Tricks 

How to Keep Things From Going 
Wrong With Your Arduino-hased Bot 

by Gordon McComb 

Not sure where to start when you need to 

diagnose a problem? This guide will help! 



64 The ASABE Student 
Robotics Competition 




by R. Steven Rainwater 
Each year, the American 
Society of Agricultural 
& Biological Engineers 
hosts a student contest 
which has a different 
agricultural theme. 
This year, participants 
had to navigate a scale 
model of a feedlot. 



69 Parallax Elev-8 
Quadcopter — Part 2: 
The Electronics Setup 

by Bryan Bergeron 

Take a look at the testing and setup of this 
flying robotics platform, including integration 
with an R/C transmitter and receiver, the 
selection and care of Li-Po batteries, plus the 
never-ending task of maintenance. 

SERVO 10.2012 5 



Mind / Iron 



by Bryan Bergeron, Editor M 



Platforms 



The pioneers in robotics faced and overcame numerous challenges. 
For example, if they wanted to develop, say, a new navigation 
algorithm, they had to first build a hardware platform. They couldn't 
simply go online and decide between dozens of off-the-shelf flying, 
swimming, crawling, and walking robotics platforms. 

Today, the issues are affordability, functionality, popularity, and 
support — largely in that order. Sometimes this isn't the best order of 
consideration, however. 

I've gone through my share of commercial platforms including 
various forms of the Parallax BoeBot, a six legged crawler and arm from 
CrustCrawler, at least two roamers from a now-defunct company, arms 
from Trossen Robotics and Lynxmotion, and flying platforms from 
Parallax, DIYDrones, and a few offshore companies. Some have been 
great time savers, and a few have been time sinks. 

The two carpet roamers (from a company I can't recall) were time 
sinks because, well, the company is defunct. That means no technical 
support, no spare parts, and no user community. It's hard to avoid this 
sort of endgame unless you know something about the company. 

The issues of affordability and functionality are easily quantified. 
Twenty minutes on the Web will reveal the best price, and user reviews 
are great for assessing functionality. The Web is also a great tool for 
assessing the popularity of a platform. Look for articles and postings 
on YouTube to give you an indication of whether you're considering a 
dinosaur or a hot platform. 

The one area in which I've stumbled lately is support. In these 
cost-cutting times, it's common to offload support to a user forum. 
Sometimes these are fantastic responsive resources. Other times, it's a 
pool of questions with no answers. Plus, it's difficult to determine the 
level of support until you have a specific problem. I've found this most 
commonly associated with open source software. 

For example, I'm working on a robotics book and needed a 
platform to illustrate some robotics principles. I identified two vendors 
of popular platforms and purchased the platform with the best 
specifications and apparently the greatest popularity among 
experimenters. Unfortunately, the software was open source and not 
supported by the hardware vendor. I wasted days trolling through the 
forums looking for an answer to an interface question without luck. 
The forum leader was away on vacation or grad school, or both 
apparently. 

In the end, I ordered the somewhat dated hardware platform with 
a commercial software library, and was up and running in minutes. 
There was a professionally edited and indexed user manual online and 
other support that you'd expect for a commercial product. I had to give 
up the bleeding edge hardware, but it wouldn't have been fair to 
readers to feature a cool looking but inoperative robot. 

I'm not suggesting that all open source software and hardware is 
suspect — I'm a fan of both. I am suggesting that you take a look at 
who or what is behind the product. Parallax, for example, sells an open 
source quadcopter, and both the hardware and Propeller software are 
amply documented and professionally supported. It's the same with the 

6 SERVO 10.2012 



FOR THE 
ROBOT 
INNOVATOR L 



?ERVO 



Published Monthly By 

T & L Publications, Inc. 

430 Princeland Ct, Corona, CA 92879- 1 300 

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FAX (951) 371-3052 

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Outside US 1-818-487-4545 

RO. Box 1 5277, N. Hollywood, CA 9 1 6 1 5 

PUBLISHER 

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publisher@servomagazine.com 

ASSOCIATE PUBLISHER/ 
VP OF SALES/MARKETING 

Robin Lemieux 
display@servomagazine.com 

EDITOR 

Bryan Bergeron 
techedit-servo@yahoo.com 

CONTRIBUTING EDITORS 



Jeff Eckert 
Tom Carroll 
Dennis Clark 
Kevin Berry 
Morgan Berry 
Gordon McComb 
Andrea Suarez 



Jenn Eckert 
David Geer 
R. Steven Rainwater 
Michael Jeffries 
Fred Eady 
Zachary Lytle 



CIRCULATION DEPARTMENT 

subscribe@servomagazine.com 

MARKETING COORDINATOR 
WEBSTORE 

Brian Kirkpatrick 
sales@servomagazine.com 

WEB CONTENT 

Michael Kaudze 
website@servomagazine.com 

ADMINISTRATIVE ASSISTANT 

Debbie Stauffacher 

PRODUCTION/GRAPHICS 

Sean Lemieux 

Copyright 20 1 2 by 
T & L Publications, Inc. 

All Rights Reserved 

All advertising is subject to publisher's approval. 
We are not responsible for mistakes, misprints, 
or typographical errors. SERVO Magazine assumes 
no responsibility for the availability or condition of 
advertised items or for the honesty of the 
advertiser. The publisher makes no claims for the 
legality of any item advertised in SERVO.This is the 
sole responsibility of the advertiser.Advertisers and 
their agencies agree to indemnify and protect the 
publisher from any and all claims, action, or expense 
arising from advertising placed in SERVO. Please 
send all editorial correspondence, UPS, overnight 
mail, and artwork to: 430 Princeland Court, 
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Printed in the USA on SFI & FSC stock, ^p-"--- V F "£ 



open source hardware and Arduino 
software from DIYDrones. 

Bottom line is that you have to 
do your homework on the quality 
of support available when you're 
considering a commercial robotics 
platform. If you have lots of free 
time and enjoy debugging 
hardware and software, then 
support may not be an issue. You'll 
probably become a super-user, 
providing much needed advice on 
the user forums. However, if you're 
looking for a platform as a means 
to your real interest in robotics, 
then make certain support is right 
up there with the technical 
specifications when you're making 
a purchase decision. 



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Discuss this article in the SERVO Magazine forums 
at http://forum.servomagazine.com. 



by Jeff and Jenn Eckert 



Turning Minutes Into Hours 

It's no secret that one of the primary constraints in 
mobile robotics is the limited power available from 
batteries. A great deal of research is aimed at improving 
battery performance, with progress reported in fields 
ranging from such novel approaches as lithium-air batteries 
to century-old technologies like nickel-iron (Edison) devices. 
Another way to tackle the problem is to improve the bot's 
output efficiency, which is the idea behind the M3 
Actuation project — a subset of the Maximum Mobility and 
Manipulation (M3) program at the Defense Advanced 
Research Projects Agency (DARPA). 

The goal is to achieve a 2,000 percent increase in 
overall efficiency. More specifically, it seems that the 
current Government Furnished Equipment (GFE) platform 
offers only 10 to 20 minutes of untethered operation, and 

DARPA wants to extend that to 200 minutes. If you think you have the know-how to come up with a solution, the reward 
could be as much as a cool $5 million. 

Offering some hints as to how to proceed, it was noted that "DARPA expects that solutions will require input from a 
broad array of scientific and engineering specialties to understand, develop, and apply actuation mechanisms inspired in 
part by humans and animals. Technical areas of interest include, but are not limited to: low-loss power modulation, 
variable recruitment of parallel transducer elements, high bandwidth variable impedance matching, adaptive inertial and 
gravitational load cancellation, and high efficiency power transmission between joints." The formal deadline for submitting 
a proposal was August 21st, but there is a six month grace period, so it's not too late to put your iron in the fire. 
"Contingent on the availability of funds," yours may still be selected. Details are available at www.darpa.mil, but you 
can just search "DARPA-BAA-1 2-52-1 .pdf" to locate the pertinent document. 




DARPA seeks a 2,000 percent increase in robot efficiency. 




Camera positioning system used by researchers at 
Georgia Tech's School of Mechanical Engineering. 
(Photo courtesy of Joshua Schultz). 



Here's Looking at You 

Another area in which bot technology is always subject to 
improvement is vision, and some folks at Georgia Tech's Woodruff 
School of Mechanical Engineering (www.me.gatech.edu) have 
harnessed the piezoelectric effect to replicate the muscle motion of 
the human eye. "For a robot to be truly bio-inspired, it should possess 
actuation, or motion generators, with properties in common with the 
musculature of biological organisms," observed Ph.D. candidate 
Joshua Schultz. "The actuators developed in our lab embody many 
properties in common with biological muscle, especially a cellular 
structure. Essentially, in the human eye muscles are controlled by 
neural impulses. Eventually, the actuators we are developing will be 
used to capture the kinematics and performance of the human eye." 

According to the developers, the new muscle-like action could 
help make robotic tools safer and more effective for MRI-guided 
surgery and robotic rehabilitation. 



8 SERVO 10.2012 



www.servomagazine.com/index.php7/magazine/article/october2012_Robytes 



Humanoid Swimbot Introduced 

Aquatic robots tend to be patterned after fish and other 
entities that are inherently good at swimming, but researchers 
at the Tokyo Institute of Technology (www.titech.ac.jp) have 
bucked the trend and built what they say is the first humanoid 
robot that can swim underwater using all four limbs. 
"Swumanoid" is a 12 lb, three ft tall half-scale version of a former 
Japanese Olympic swimmer who apparently wants to remain 
anonymous. The aquabot's mission is to figure out how to create 
the least amount of drag while swimming, thus potentially 
teaching us how to do a better job of it. For example, the Tok *° Tech s Swu ™"° id <" ot ™ d Y f° r the Olympics). 

researchers will study how pulling its arms straight through the water compares with using a zig-zag pattern. Although powered 
by 20 motors, Swumanoid plods along at a measly 0.64 m/s (2.1 fps), compared to Nathan Adrian's 2.1 m/s (6.9 fps) in the 
summer Olympics 100 m freestyle. Its creator says that Swumanoid 2.0 — due sometime next year — will improve upon that. 




Robotic Architectural Printer 



We had to view this item with a bit of skepticism, especially given that the documentation includes some obvious 
Photoshop concoctions. According to the website of the Institute for Advanced Architecture of Catalonia (www.iaac.net) , 
it's for real. Building on the concept of 3D printing, some students came up with the idea of building architectural 
structures by spraying a mixture of dirt and a liquid binder to create a variety of solid forms and shapes. Moreover, the 
"Stone Spray" process is carried out by robots, can be powered entirely with solar energy, and employs nontoxic 

PolyPavement (www.polypavement.com) as the binder. 
It's a little early to think about spraying yourself a new 
beach bungalow, though, as the process seems to still have 
a few bugs in it (perhaps literally). For example, the "stool" 
shown in the photo required an internal wire skeleton, and 
it took four hours to create and solidify it, even though it 
measures only 200 mm in all dimensions. Such a structure 
is said to be "structurally strong and can support not only 
itself but even bear a load," but how much of a load is still 
Stone Spray process. in question. Still, it's an interesting concept. 




Art Imitates Imitation Life 

Finally, as we have observed upon occasion, whenever you mix art, 
robotics, and public funding, strange things can happen. In this case, it is 
a sculpture by Czech artist David Cerny, consisting of a six ton, 1957 
double-decker bus that does push-ups. Also featured are video projections 
in the windows and recorded groaning sounds. The work of art was 
created as a tribute to the London Olympic games and is located outside 
of the Czech Olympic House (which usually havens the Business Design 
Center) in London. Explaining the point of the artwork, the artist noted 
that the push-up "is training for sport activities but at the same time it is 
also punishment in armies and prisons. So, the push-ups are a very 
universal physical activity ... It is in a way very ironic." Now don't you feel 
enlightened? 

Previous Cerny creations include an object depicting Bulgaria as a 
squat toilet, a statue of Saddam Hussein floating in formaldehyde, and a 
display encouraging people to kill each other to control population 
growth. SV 




"London Boosted," a piece of robotic art 
by David Cerny. 



SERVO 10.2012 9 



1 



by David Geer 



LnJLs 

Contact the author at geercom@windstream.net 



.**?* 



- .+&&* 

#&&* 



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Collaborating 
With HUBO 



Dr. Youngmoo Kim and Dr. Paul Oh of 
Drexel University are working with 
HUBO robot platforms from the Korea 
Advanced Institute of Science and 
Technology (KAIST) to help advance the 
development of humanoid robotics. By 
sharing seven standardized HUBO 
robots among Drexel University, MIT, 
Carnegie-Mellon, Virginia Tech, the 
University of Southern California, Ohio 
State, Purdue, and Penn State, each 
school is able to work on and improve 
differing types of algorithms, 
programming, behaviors, and 
capabilities on its robot while ensuring 
that progress at one school translates to 
the robots at the other schools. A grant 
from the NSF made it all possible. 
At Drexel, Dr. Kim (the Director of the 
Music and Entertainment Technology Lab) is working on musical development 
on the HUBO platform which we'll take a look at later in this article. 




The HUBO Platform 

The first HUBO was part of a previous project that 
Dr. Oh kicked off. It was a multi-million dollar project to 
bring HUBO from KAIST to Drexel, and to trade students 
between KAIST and Drexel to share knowledge and training 
on HUBO. 

The HUBO robot platform is a four foot, three inch tall, 

10 SERVO 10.2012 



fully actuated humanoid robot with similar joint movement 
to that of humans. HUBO's legs, arms, hands, fingers, and 
thumbs work about the same as human's do, as well. HUBO 
and HUBO 2 are among the latest robots in the HUBO 
series, showcasing a slighter design consisting of a 
polycarbonate frame and an aluminum endoskeleton. The 
new HUBO is taller and lighter. For this version, KAIST made 
improvements in the mechatronics for greater reliability. 



www.servomagazine.com/index.php7/magazine/article/october2012_GeerHead 



GEERHEAD 




The new HUBO is enabled with much more human-like 
motor skills including faster, more realistic arm movement 
and stretching legs that mimic human bi-pedal movement 
more closely. Natural human walking requires less energy 
than typical robot walking, so there is an energy savings. 
This is calculated using the Zero Moment Point trajectory 
calculation. The HUBO robot now has an increased walking 
speed of 1 .4 km per hour and can now run at up to 3.6 km 
per hour. 

The new HUBO platform leverages the following 
technologies: a smart power distributor and lithium polymer 
battery that is +48V, 8A; a shape adaptive hand that is 
tendon-driven with five fingers (one degree of freedom per 
finger) and an F/T sensor at the three degree of freedom 
wrist; an IMU (two axis) with Kalrman filtering and a rate 
gyro and accelerometer; a two channel BLDC controller that 
is 90 mm x 65 mm with a 16-bit microprocessor; a CAN 
interface; an A/D converter; over-current protection; 
automatic return to initial position; a BLDC motor amplifier 
that is 90 mm x 90 mm 200W and 48V; and a full bridge 
MOSFET. 

Drexel received one HUBO initially and six HUBO 2s 
later on. The last six are identical but they each have 
individual quirks. One has an ankle motor that is a little off; 
another has a different computer inside, but the platform is 
otherwise the same, says Dr. Kim. Drexel has given each 
one a number to tell them apart. 

The first of the two HUBOs (introduced in 2004) did 
not have the power efficiency, custom hardware, and circuit 



boards available on the newer HUBO 2. The HUBO 2 
operates on battery power for nearly an hour. KAIST has 
lowered the center of gravity on this robot so that it will 
not fall over so easily. HUBO 2 has increased motor 
efficiency and faster processors in its internal computer. 
One of those processors is a standard PC 104 platform 
base. There is room for two processors in the robot: one for 
command, control, and movement; and the other for 
sensing, cognition, and higher-level tasks. "The challenge is 
in having the two processors communicate with each 
other," comments Dr. Kim. 

The Research 

Dr. Kim has developed algorithms for tracking the beat 
in music based on the audio. This is a hard problem to 
solve. It is difficult to teach a computerized robot to do that 
in a robust way. "We are working on having the HUBO 
robots play simple percussion instruments that we have 
built out of PVC pipe. We are working on having them play 
the notes and listen to the notes to see whether a note was 
a good note. This involves audio and force feedback 
capabilities," explains Dr. Kim. 

Dr. Kim is using machine learning and as HUBO makes 
lots of differing strikes on the instruments, Dr. Kim presents 
some to the robot and tells it that these were good or bad 
notes. The force feedback sensing from the robot's hand 
and wrist together with the sound of the note tell the 
characteristics of the different notes. 

SERVO 10.2012 11 



GEERHEAD 




Photo from the day 

3 that Drexel 

£ University set up 
fouroftheHUBO 

§3 robots to pose as if 
crossing the street 
like the Beatles 
from their Abbey 
Road album* 



12 SERVO 10.2012 



Some videos of HUBO on YouTube 
include the robots playing "Come Together" 
from the Abbey Road album by the Beatles. 
Dr. Kim and colleagues took a photo of the 
HUBO robots crossing the street so that it 
looked like the Abbey Road album cover. The 
photo appeared on the cover of the Drexel 
online magazine last spring. 

While Dr. Kim has developed the beat 
tracking capabilities for HUBO, he has not 
perfected the robot's dancing capabilities. 
"The HUBOs cannot dance in a good, 
realistic way yet. They can perform 
programmed gestures at the right time. 
The goal is to have them perform the right 
dancing gestures linked together in the right 
way with some creativity," says Dr. Kim. 

The gesture and motion planning for 
dancing is a very complicated problem 
that is similar in complexity to the motion 
planning for having robots work with tools 
or operate doors and latches. 

The long-term goal of Dr. Kim's research 
is to have the robots play musical 
instruments alongside human musicians in 
an ensemble. "We eventually want robots to 
be autonomous enough to be personal 
assistants, help people get around, do 
dishes, clean up, and fold laundry. We are 
taking steps in that direction, as well," 
comments Dr. Kim. 

The HUBO robot is physically capable 
of these things. It can deal with curbs and 
stairs (walking), and can use its fully 
actuated hands to pick up light objects, 
including tools. "These are all individual 
capabilities. Linking them together takes 
baby steps," expressed Dr. Kim. 



- Advances 



Most recently, Dr. Kim and colleagues 
have made a lot of strides in the listening 
capabilities of the HUBO 2 robot. As the 
robots move, they make a certain amount 
of noise, so while they are trying to do 
something such as move or interact with 
other musicians, if someone is talking in the 
background as well, the motor noise makes 
it difficult for the robot to discern one sound 
from another. "We have worked out a 
couple of different algorithms to rid the 
noise," explains Dr. Kim. He is also using 
better microphones that are directional, and 
filter out unwanted noise while filtering in 
the desired sounds. "We are working on a 



GEERHEAD 



microphone array for HUBO for this," affirmed Dr. Kim. 

He is also employing a two-lense binocular camera with 
a high frame rate of 45-60 fpc to enable the high tracking 
rate that is necessary for some of these tasks. 

Dr. Oh is working on mobility tasks for HUBO, such as 
climbing stairs and dealing with uneven terrain (though the 
robot is not very good at the latter task just yet). Dr. Oh 
is also developing the HUBO platform for skills like 
human-robot "teaming," such as helping a human carry 
a table. The robot will need to walk together with the 
human to move objects from one spot to another. 

Dr. Oh is brainstorming on a lot of different strategies 
for that, and is also working on the challenge of having 
two robots move a table together without the aid of a 
human. 

In addition, the researchers are working on speech 
recognition for HUBO using a standard speech recognition 
tool, though there are issues around acoustics and — again 
— noise. USC is working on adding touch-based sensing 
together with a company called SynTouch. 

Conclusion 

According to Dr. Kim, it will take about five to 10 years 
to get the HUBOs to play musical instruments together with 



Resources 



Dr. Youngmoo Kim 
http://music.ece.drexel.edu/people/ykim 

Dr. Paul Oh 
http://dasl.mem.drexel.edu/people.php 

YouTube video including HUBO 2 and related work 
www.youtube.com/watch?v=dJRzJt-Pwfc 

Drexel Autonomous Systems Lab 
http://dasl.mem.drexel.edu/ 

HUBO 1 accompanying music 

www»youtube.com/watch?feature=endscreen& 

NR=1&v=L21_YZvd6Ck 

HUBO 2 robots dancing 
www.youtube.com/watch?v=PLn_BGfP84g 



human musicians. "The more general problems like 
autonomous robot assistance, such as HUBO moving 
around in someone's home — that is a 10-20 year range 
problem. And everyone having a complex, commoditized 
humanoid robot in their home to help with multiple 
complex tasks, well, that is a 20-40 year range problem 
before we solve it," Dr. Kim concluded. 



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SERVO 10.2012 13 



p ■ ■ ■ 





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f 

sident expert on all things 
robotic is merely an email away. 
boto@servomagazine.com 



Tap into the sum of all human knowladga and get your questions answered here! 
From software algorithms to material selection, Mr. Roboto strives to meet you 
where you are - and what more would you expect from a complex service droid? 

by 
Dennis Clark 




As I write this, I have just 
returned from the Microchip 
Master's Conference 2012, 
and boy was that a blast. I 
should qualify that statement. It was a 
blast for a seriously geek crowd of 
hardware and firmware engineers that 
really love their work of making things 
that do stuff. The chipKIT folks at 
Digilent had some very fun classes and 
I discovered a seriously cool product 
series by Roving Networks that puts an 
entire Wi-Fi stack on a very affordable 
module. I'll be writing about that in a 
little bit, but first, I have some 
observations to make. The crowd 
going to these events is looking 
"grayer." We need more younger 
engineers coming into the "club" 
which leads me to my next set of 
musings ... 

For many years now, I have been 
lamenting to anyone who would listen 
(a shrinking crowd) that today's kids 
aren't interested in how things work 
and how to make them. They are only 
interested in using the cool new 
gadgets that our technology wizards 
are creating for the consumer market. 
My concern was further fueled by an 
article in EETimes by Bill Schweber in 
2008 which asked the question: "Are 
we becoming a 'Cargo Cult'?" 
Schweber goes on to describe a cargo 
cult which originated with a story 
about Pacific Island natives in WWII 
who built dummy replicas of radios, 
antennas, and microphones to call for 



planes to land with their desired 
cargo, just like they saw the military 
forces doing. The natives didn't 
understand what was behind the 
technology they saw being used; they 
just saw things happen when it was 
used. Does that sound familiar to you 
with respect to our smartphone 
carrying society? 



As more and more high 
technology is created by a 
shrinking pool of those who 
understand how to create and 
maintain these nearly magical 
marvels, are we allowing 
ourselves to simply go through 
the motions of understanding 
how our society's underpinnings 
work? That is a kind of scary 
thought, isn't it? There are 
plenty of Orwellian scenarios to 
play out in my mind dealing with 
that concept How about yours? 



Now that I have ruined your 
night's sleep, let me try to allay your 
fears! In the last few years, I've seen a 
reversal of that trend forming. I am 
referring to — of course — the "maker" 
renaissance that has been born in 
many places. The first (pun intended) 
origin I believe is Dean Ka men's 
FIRST organization, which spawned 
the First LEGO League. FLL hopes 
to create the next generation of 
our society's engineers and 



entrepreneurs. Later, came the rise of 
the maker folks from Make Magazine 
and the Maker events that happen 
all around the world. The maker 
movement is all about creating new 
things of beauty and usefulness 
without needing huge corporate 
backing. 

I place the Arduino "cult" firmly in 
the midst of the maker movement for 
bringing together ideas from many 
places to create the Arduino platform 
that help those who didn't start out as 
embedded engineers to make tools 
and art that use embedded 
engineering tools of the trade. Bravo. 
Now, we have lots of spinoffs of the 
Arduino scene for hardware and 
creative aids like the on-line site 
Instructables to boost that maker spirit 
out there. 

This movement has given me back 
hope that our society can still improve 
and move forward from many creative 
origins and has not given up our 
future to the faceless mega- 
corporations of the world. Okay, so 
maybe that was a bit strong, but still, 
the small operations out there catering 
to the maker movement have been 
embraced and are successful because 
our culture has NOT become a cargo 
cult. We still seek to create and to 
understand. I tell my children that not 
all "magic" comes from fantasy books. 
The technological creations of our age 
are just as wondrous as any spell from 
a magic wand in a book. 'Nuff said! 



14 SERVO 10.2012 



www.servomagazine.com/index.php7/magazine/article/october2012_MrRoboto 



New and Cool From 
the Conference 

Now, on with the nifty new 
things that I saw at my Geekfest, er, 
conference, that is ... 

The Digilent people who created 
the UN032 and MAX32 Arduino 
compatible boards, along with the 
Rutgers gentlemen who helped create 
the MPIDE extension to the Arduino 
IDE, have been busy making the 
chipKIT boards even more compatible 
with Arduino scripts and hardware. 
Digilent has come up with both 
Internet client-side and server-side 
APIs for their chipKIT boards. This 
library works with a variety of their 
Pmod Internet boards and their 
UN032 Wi-Fi shield, as well. It is my 
understanding that they have kept 
that library true to the original 
network library created for Arduino, 
and corrected and extended it for the 
faster UN032 and MAX32 boards. I 
was drinking from the fire hydrant 
there, so I'll do some articles in the 
future that go into more detail with 
examples and code in coming 
months. The Digilent folks have also 
extended their Arduino-like chipKIT 
boards — the Cerebot — to use more 
of the Arduino libraries. In general, if 
you create Arduino scripts using the 
standard hardware abstraction layer 
and don't optimize for the AVR 
hardware, your scripts will work on 
both Arduino and chipKIT hardware. I 
like that. I was seeing a lot of things 
related to networking and especially 
wireless networking. Go to 
www.digilentinc.com to get more 
information about this and other fun 
things these guys are doing. 

The other bug I'd like to drop in 
your ear is the Roving Networks Wi-Fi 
module. This is an entire Wi-Fi 
Internet stack on a tiny board that 
you talk to over a digital UART or SPI 
connection at up to 2 MB/s. Imagine 
giving your robot a Wi-Fi connection 
to your laptop or other devices by 
adding a board by simply plugging in 
a motor controller. I've GOT to get 
me a couple of these! To get one for 




yourself to play with, order the 
developer's kit (part number RN- 
1 74K) from www.microchip 
direct.com or from the Roving 
Networks site at www.roving 
networks.com . 

That was all fun, but I'm going to 
go back to last month's topic for a 
moment and the wireless PS2 
controller quest. 

I'll write about these and other 
devices that are really handy and easy 
to use for our robot projects in later 
columns, so stay tuned! 

The Continuing Saga 
of the Quest for 
the Perfect PS2 
Wireless Controller 

When last we met, I had found 
my first working wireless PS2 
controller by buying a new GameStop 
Predator S-Type unit that was all 
digital except for the joysticks. At that 
time, I had bought (but not yet 
received) a Lynxmotion wireless PS2 
controller for US$19.99 - the same 
price as the GameStop unit. The 
Lynxmotion PS2 controller was larger, 
meatier, and was (sigh) the proper 
Darth Vader black color (see 
Figure 1). The one down-side to the 
Lynxmotion unit is that its wireless 
module was the largest of all of the 



Figure I. 



units I've tested. However, every 
single button was fully analog 
pressure sensing except for the 
"Select" and "Start" buttons. The 
harder you pressed, the bigger the 
number that was returned. If you are 
looking for a controller that responds 
to the emotional "pressure" of its 
holder, this would be the unit! All of 
the buttons also gave their digital 
values to the button registers, so you 
could use this controller any way you 
wanted. It even has the "rumble" 
motors in it, so you could have your 
robot give haptic feedback when it 
hits something or wants your 
attention. (Hmm, that sounds like a 
neat idea!) 

This month, I'm going to modify 
the Arduino PS2 library demo test 
code to read the joysticks and drive a 
small tracked vehicle around. The final 
use for this device will be to drive one 
of my humanoid bipeds — I'll publish 
details about that when I get it done. 
For the sake of this column, I'll be 
driving a hacked toy chassis around. I 
don't remember what toy this was or 
even when in my evil hacking days I 
stripped away all but the drive train, 
but it was on top of my junk box and 
had two motors so I used it. It even 
has tank treads which I think are cool, 
so that sealed the deal. Since I'm 
using an Arduino, my first thought 
was to call this project the YAAR for 

SERVO 10.2012 15 



Discuss this article in the SERVO Magazine forums at http://forum.servomaqazine.com 




Figure 2. 



Yet Another Arduino Robot. (But, wait! I'm driving it 
and I firmly reject the idea that any remotely 
controlled vehicle is a robot! Not to worry. The 
acronym can still be Yet Another Arduino Remote 
vehicle. So, YAAR it is.) 

As with last month's PS2 project, I'm using a 
SparkFun Arduino Pro (a 5V Arduino running at 16 
MHz) and the Arduino 1.01 IDE. This script will work 
with any Arduino Uno board, as well. 

To make this project, all I need to add is a vehicle 
chassis and a low voltage dual motor controller. I like 
to fly electric RC aircraft, so I have no shortage of two 
and three cell lithium-ion battery packs lying around, 
but I didn't have any simple-to-use reversing low 
voltage motor controllers. Time to hit the Web. I 
found the Pololu TB6612FNG motor controller for 
about US$9. It is a one amp continuous 3A peak 
controller for motors in the 4.5V to 13V range and it 
is TINY! Figure 2 shows the board with some 
connectors attached. This comes semi-assembled; you 
have to install whatever connectors or wires you want 
to use. 

I simply used the included "Berg" headers for this 
project since I knew that I was going to be using a 
solderless breadboard to simplify my wiring needs. 
The pins are very clearly labeled on the bottom of the 
board (again see Figure 2). To make my little 
demonstration vehicle, I needed to use four I/O lines 
for the PS2 controller and six I/O lines for the motor 
driver board. That leaves just two digital I/O lines: the 
serial port and the analog lines. Not much left to 
make a robot with! But, as I said, this is a "proof of 
concept" design, so I'll leave the I/O line optimization 



Listing 1. 






byte leftDir = 0; 
byte rightDir = 0; 




#include <PS2X_lib.h> //for vl 


6 




void setup ( ) 
{ 

pinMode( IDirl, OUTPUT); 

pinMode(lDir2, OUTPUT); 

pinMode (rDirl, OUTPUT); 

pinMode(rDir2, OUTPUT); 

pinMode (PWML, OUTPUT); 

p i nMo de ( PWMR , OUTPUT ) ; 

analogWrite ( PWML , ) ; 
analogWrite (PWMR, 0) ; 




// Left motor driver I/O lines 
const int iDirl = 2; 
const int lDir2 = 3 ; 
const int PWML = 5; 

// right motor driver I/O lines 
const int rDirl = 4; 
const int rDir2 = 11; 
const int PWMR = 6; 








// create PS2 Controller Class 
PS2X ps2x; 

/* 

* You must have the controller 

* when this program starts. 
*/ 

int error = ; 
byte type = 0; 
byte vibrate = 0; 


turned 


on 


Serial. begin(57600) ; 

// GamePad (clock, command, attention, data, 
// Pressures?, Rumble?) 

error = ps2x. conf ig_gamepad ( 7 , 9 , 8 , 10 , true, 
true) ; 








if (error == ) { 

Serial .println ( "Found Controller, configured 




// Full forward == 0, full reverse == 
byte leftSpeed, rightSpeed; 


255 


successful " ) ; 
} 
else if (error == 1) { 





16 SERVO 10.2012 



as an exercise for the student (smile). 
Figure 3 shows the (literal) rats nest of wiring I needed to 
make my remote vehicle. People ask why it is so hard to 
make a robot — all the wires, man! All the wires! 

The last little bit of hardware I used to complete my 
design is a Hobby People two-cell, 25C 850 mAh Li-Po 
battery pack. At full charge, this pack is about 8.4V which 
is plenty of voltage for my vehicle motors and still well 
below the 13V maximum for the motor driver chip I'm 
using. Since most motor controllers don't sense the voltage 
and shut down before damaging the pack, remember you 
need to watch your lithium-ion pack's voltage. If the 
battery is drained below about 2.5V (depends on the 



Arduino Pin Number 




Function 




7 


PS2 SPI clock 


8 


PS2 ATN line 


9 


PS2 CMD line 


10 


PS2 Data line 


2 


Dir1 A for the left motor 


3 


Dir2A for the left motor 


5 


PWMA for the left motor 


4 


Dir1 B for the right motor 


11 


Dir2B for the right motor 


6 


PWMB for the right motor 


Table 1. Arduino I/O pin assignments. 



Serial .println ( "No controller found, check 
wiring, see readme.txt to enable debug, 
visit www.billporter.info for troubleshooting 
tips" ) ; 

} 

else if (error == 2) { 

Serial .println ( "Controller found but not 
accepting commands, see readme.txt to enable 
debug. Visit www.billporter.info for 
troubleshooting tips"); 

} 

else if (error == 3) { 

Serial .println ( "Controller refusing to enter 
Pressures mode, may not support it. "); 

} 

type = ps2x. readType ( ) ; 
switch (type) { 
case : 

Serial .println ( "Unknown Controller 

type " ) ; 

break; 
case 1: 

Serial .println ( "DualShock Controller 

Found" ) ; 

break; 
case 2 : 

Serial .println ( "GuitarHero Controller 

Found" ) ; 

break; 
} 



} 

void loop ( ) 
{ 



r 



You must Read Gamepad to get new values 
you should call this at least once a 
second 



V 



if (error == 
return; 
/* 



1) //skip loop if no controller 
//found 



* Read controller and set large motor to 

* 'vibrate' 

* this will set the large motor vibrate 

* speed based on 

* how hard you press the blue (X) button. 
*/ 

ps2x. read_gamepad ( false, vibrate) ; 
vibrate = ps2x. Analog (PSAB_BLUE) ; 



some dead band around the center and 

adjust the 

values to send to the PWM around 0-126. 

Not too 

fast. 

leftSpeed = ps2x. Analog (PSS_LY) ; 

// left 

if (leftSpeed > 130) { 

leftSpeed -= 128; 

leftDir = 1; 

// reverse 
} 
else if (leftSpeed < 126) { 

leftSpeed = 126 - leftSpeed; 

leftDir = 0; 

// forward 
} 

else { 
// call it stopped 

leftSpeed = 0; 

leftDir = 1; 
} 

// Now set the driver direction lines and 
// PWM 

digitalWrite(lDirl, leftDir & 0x01); 
digitalWrite(lDir2, -leftDir & 0x01); 
analogWrite (PWML, leftSpeed) ; 

rightSpeed = ps2x. Analog (PSS_RY) ; 

// right 

if (rightSpeed > 130) { 

rightSpeed -= 130; 

rightDir = 1; 

// reverse 
} 
else if (rightSpeed < 126) { 

rightSpeed = 126 - rightSpeed; 

rightDir =0; // forward 

} 
else { 

rightSpeed = 0; 

// stop 

rightDir = 1; 
} 

// Set motor driver directions and PWM 
digitalWrite(rDirl, rightDir & 0x01); 
digitalWrite (rDir2 , -rightDir & 0x01); 
analogWrite (PWMR, rightSpeed) ; 

// Some debug output 
//Serial. print (leftSpeed, DEC) ; 
//Serial .println (rightSpeed, DEC) ; 



delay (50) 



Get the stick Y axis, 
leave 



128 is center, 



} 



SERVO 10.2012 17 




battery), then the pack is dead and not recoverable. 

Now, it's time to look at the program that you need to 



hardware abstraction 
the job. 



Figure 3. 



handle this most basic of remote 
control operations. I am only looking 
at the Y axis joystick values so that I 
can drive my vehicle like a tank. 
Because I thought it was cool, I've 
left in the rumble ability. I could put a 
collision detector sensor on the thing 
and have it "rumble" my controller 
when something gets close. Cool, a 
haptic feedback device! Listing 1 
shows my code. It is cribbed from the 
demo code that comes with the PS2X 
Arduino library and modified to drive 
the motors on YAAR. 

I've included the entire script here 
since — this being an Arduino — I 
don't need to explain how to set up 
PWM registers, set timers, mask I/O 
bits, and all the other "stuff" that an 
embedded program has to do before 
anything useful happens. The Arduino 
API hides those details behind its 
layer, so you can focus on just doing 



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The first code block defines all of our 
I/O lines and the PS2 controller object. 
The SetupQ block configures the I/O lines 
and discovers which PS2 controller you 
are using. Finally, the LoopQ block is the 
code that controls everything in real time. 
Notice at the top of the loop I left in a 
way to make the controller rumble if you 
push the blue "X" button on the right of 
the PS2 controller. Push it a little and it 
rumbles a little; push it a lot and, well, 
you get the idea. I left that in so you 
could experiment with having a sensor 
give some user feedback. 

To get everything to work properly, 
turn on the PS2 controller, then power up 
the YAAR after you connect the battery. 
The blinking red LED on the wireless 
module will stop blinking and turn solid 
when the remote and the module have 
connected. Now go drive! Figure 4 is a 
picture of my monster. It isn't pretty, but it works great! 

Well, that's it for another month. Keep building robots 
and if you get stumped, drop me an email. As usual, if you 




have any questions for Mr. Roboto, feel free to email me at 
roboto@servomaqazine.com and I'll be happy to try to 
answer it! SV 



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SERVO 10.2012 19 




Calendar 1 



ROBOTS NIET 



Send updates, new listings, corrections, complaints, and suggestions to: steve@ncc.com or FAX 972-404-0269 



Know of any robot competitions I've missed? Is your 
local school or robot group planning a contest? Send an 
email to steve@ncc.com and tell me about it. Be sure to 
include the date and location of your contest. If you have 
a website with contest info, send along the URL as well, 
so we can tell everyone else about it. 

For last-minute updates and changes, you can always 
find the most recent version of the Robot Competition 
FAQ at Robots.net: http://robots.net/rcfaq.html. 

— R. Steven Rainwater 



OCTOBER 

1 -4 UAV Outback Challenge 

Kingaroy, Australia 

Search and Rescue Challenge, Airborne Delivery 

Challenge, and Autonomous. 

www.uavoutbackchallenge.com.au 

5-"7 MindSpark 

Pune, India 

Events include Micromouse, robot dog fights, 

and robot search and destroy. 

www.mind-spark.org 

B The Franklin Cup 

Philadelphia, PA 

Remote control vehicle combat. 

www.nerc.us 

1 S- Latin American Robotics Competition 

21 Fortaleza, Brazil 

Events include the Brazilian Robotics 
Competition, Robocup Latin American Open, 
and Brazilian Robotics Fair. 
www.cbrobotica.org 

1 9- Critter Crunch 

21 Hyatt Regency Tech Center, Denver, CO 

The original remote control vehicle 
combat event. 
www.milehicon.org 



l\IOVEI\/IB 

3 



R 



Atlanta Hobby Robot Club (AHRC) Robot Rally 

Pinckneyville Community Center, Norcross, GA 
Events include line maze solving, mini Sumo, and 
the Robot Polyathlon. The polyathlon is made up 
of six individual contests: Advanced Line Follower, 
Beacon Killer, Beacon Killer with Obstacles, 
Navigation by Dead Reckoning, and Bulldozer. 
www.botlanta.org/robot-rally 



23- All Japan Micromouse Contest 

25 Toyosu, Koto-ku, Japan 

Events for autonomous robots including 
classic Micromouse, half-size Micromouse, 
and robot race. 
www.ntf.or.jp/mouse 

23- Robotex 

25 Tallinn, Estonia 

This is the largest autonomous robot 
competition in Estonia. This year's events 
include robot football, line following, mini Sumo, 
and LEGO Sumo. 
www.robotex.ee 

25 Robocon 

Tokyo, Japan 

Student teams from all over Japan come 

together at Robocon, where the robots they've 

designed compete in the Robo Bowl. 

www.official-robocon.com 



DECEMBER 

1 -2 South's BEST Competition 

Auburn University, Auburn, AL 

Regional for the BEST student competition. 

www.southsbest.org/site 

1 5 Robotic Arena 

Wroclaw, Poland 

Lots of events including mini Sumo, micro Sumo, 

nano Sumo, Micromouse, line following, and 

freestyle. 

www.roboticarena.org 



20 SERVO 10.2012 



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HEW PRODUCTS 



MaKey Makey Invention Kits 




^parkFun Electronics is now shipping the MaKey MaKey — 
wa new product that invites everyone to be an inventor. 

MaKey MaKey was designed by MIT graduate students 
Jay Silver and Jay Rosenbaum, and is an invention kit that 
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"The MaKey MaKey is an amazing kit because it really 
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cable. The deluxe kit ($49.95) includes everything that the 
basic kit does, in addition to a second alligator clip pack, a 
jumper wires pack, and a roll of copper tape for even more 
possibilities. 

For further information, please contact: 

Sp arkFun Ele c tronic s website: www.sparkfun.com 

22 SERVO 10.2012 



PS/2 Keyboard to ASCII 
Converter Module 

>^HiPdesign announces the availability of the E1 1 1 5 — 
^a compact PS/2 keyboard to ASCII converter module 
for embedded microcontroller applications. It offloads the 
process-intensive PS/2 scancode decoding, while providing 
a fast single byte output response for both ASCII and 
non-ASCII keys including multi-media. Requiring only 
+5V, the easy to use module provides a pin selectable 
57.6K/1 1 5.2K baud rate, as well as a 1 00 kHz clocked serial 
data output. The module also flashes an LED and generates 
an interrupt pulse. 




The converter allows for the quick development of any 
keyboard-based project. The E1 1 15B is available as a 10-pin 
DIP style 1.3" x 0.7" module with integrated PS/2 connector, 
and also as a SOIC-14 chip. An application note on the 
website describes how to parse the output into commands 
and data. Pricing starts at $16 for the module and $8 for 
the chip. 

For further information, please contact: 



CHiPdesign 



Website: www,CHiPdesign t ca 



Text To 
Speech IC 

Fhe SPO-512 RoboVoice 
text to speech IC 
from Speech Chips is a 
pre-programmed 
microcontroller that 
accepts English text from a serial connection, converts that 
text to phoneme codes, then generates audio. It is ideal for 
adding a robot voice to embedded designs. 
Features include: 




• Single chip text to speech IC. 

• Low power. 

• Communicates using a simple serial port (9600 N81). 

• 800 rules that convert English text into phoneme 
codes. 

• Built-in 16-bit at 16 kHz DAC. No external filter 
required. 

The RoboVoice is based on the Microchip 
dsPIC33FJ64GP802 microcontroller. A datasheet is available 
at ww1 ■microchip.com/downloads/en/DeviceDoc/ 

70292F.pdf. User's should refer to this document for 
greater detail about the chip itself. 

Source code licenses are available. The complete text to 
speech system fits in about 32K and is written in ANSI C, so 
it can be ported to almost any embedded processor. Price is 
$24.99 each. 

For further information, please contact: 



Speech Chips 



Website: www,speechchips,com 



Servo Hub and Precision 
Disk Wheels 

^ervoCity introduces their new .770" aluminum servo 
whubs. These new hubs are machined from 7075 T6 
aluminum and have eight 6-32 tapped orbital holes that 
allow users to attach any of ServoCity's components that 
have the .770" pattern. They mate up perfectly with 
ServoCity's line of gears, sprockets, pulleys, and wheels 
which utilize the same .770" hub pattern. The aluminum 
servo hubs have broached splines to allow for a solid 
connection to any standard size Hitec or Futaba spline. The 
1/2" diameter protrusion in the center of the hubs ensures 
that the attachment is perfectly centered. 




In order to complement the new aluminum servo hubs, 
ServoCity has updated its entire line of precision disk 
wheels to incorporate the new .770" hub pattern. The 
precision disk wheels are offered in a wide variety of colors 
and diameters. The wheels provide excellent traction due to 
the rubber ring which surrounds the wheel. Each wheel is 
capable of holding up to 15 lbs without flexing. 




0.770" Gears and Sprockets 

^ervoCity has also updated their line of plastic gears and 
Vsprockets. The gears and sprockets now utilize the .770" 
hub pattern with 6-32 holes and a 1/2" center bore which is 
used throughout their entire line of products. The gears are 
constructed of acetyl and are offered in 1/8", as well as 
3/16" face width, 32 and 48 pitch, and a vast range of 
sizes in order to fit almost any application. Like the hub 
gears, the new hub sprockets are constructed of acetyl for 
superior strength and durability. The sprockets are .100" 
thick and accept standard .250" (1/4") chain. 
For further information, please contact: 



ServoCity 



Website: www,servocityxom 



Wi-Fi Gateway Module Connects 
Devices to the Internet 

tM | izFi63 ° is a h '9 h 
Wperformance 

embedded Wi-Fi 

gateway module 

available from Saelig Co. 

that transforms RS-232 

and TCP/IP protocols 

into the IEEE802.11 

b/g/n wireless LAN 

protocol. WizFi630 

enables a device with an 

RS-232 serial interface to 

connect to LAN or 

WLAN for remote 

control, measurement, 

and administration. WizFi630 can also operate as an IP 

router due to its internally embedded switch. 

WizFi630 uses serial (UART), LAN, and Wi-Fi (WLAN) 

interfaces to perform functions such as serial-to-Wi-Fi, serial- 

to-Ethernet, and Ethernet-to-Wi-Fi. Users can connect to 

WizFi630's internal web server and use simple serial 

commands to change Wi-Fi settings. In addition to serial 

devices, 8/16/32-bit microcontrollers can use WizFi630's 

SERVO 10.2012 23 




UART interface for Wi-Fi functions. WizFi630 can operate in 
Gateway, AP, AP-Client, Client, and AD-HOC modes, and 
offers 2x UART and 3x Ethernet interfaces. 

WizFi630 can simplify wireless module tasks like design, 
testing, and certification, and offers a fast solution for users 
who lack wireless network experience. WizFi630 follows the 
802.1 1b/g/n standard, and supports wireless interface 
transfer speeds of up to 150 Mbps. Configuration as a 
built-in web server is easy via serial commands from the 
Windows utility software provided. WizFi630 is CE and 
FCC certified. 

A WizFi630 evaluation board with ready-made interface 
connectors is available providing a complete test set-up with 
PC software and documentation, enabling anyone to 
quickly develop a wireless solution. 

Applications for WizFi630 are wide ranging. For a 4G 
LTE repeater, WizFi630 can function as a serial-to-Wi-Fi 
access point; for routine management and upgrade of the 
repeater, WizFi630 provides serial-to-Wi-Fi gateway function, 
but can also enable a laptop or smartphone to access the 
repeater without using an additional access point. As a 
hotel room controller, WizFi630 can be used as an Ethernet- 
to-Wi-Fi AP-Client; in hotel room control, WizFi630 provides 
a multi-networking environment by combining Wi-Fi and 
Ethernet connections. Users can control lighting, TVs, or 
any electric devices in the room via Wi-Fi, and have Internet 
connection, as well. 

WizFi630 Wi-Fi modules are available now starting at 
$35, with evaluation boards priced at $98. 

For further information, please contact: 



Saelig 



Website: www.saelig.com 



Grippers, Foot Weights, 
and Crawler Kits 

JfJoboBrothers, Inc., has three new products available for 
r wobot builders. 

The Philo Gripper is an easy drop-in replacement for a 
forearm, with two servos for grip and wrist turning. It also 
includes a torque limiter to protect the gripping servo and 
a silicon tip for better gripping force. Pre-assembled versions 
and kits are available. 




Also new are their RoboPhilo foot weights. The kit 
includes two sets of weights and double-sided tape. This 
product adds weight to the foot areas, so provides more 
stable motion. 




The RoboCrawler is a simplified robotic crawler which 
offers an affordable option to hobbyists interested in 
multi-legged walkers. 




!L hoi o - 

im. H 



Features include: 

• Eight servos for eight degrees of freedom for the 
legs. 

• Each motion routine can have up to 30 sequences, 
and each sequence can have up to 15 poses. 

• Sequence and pose can be reused for other motions 
to save Flash memories. 

• One motion routine can have up to 450 pose 
transitions. 

• RS-232 serial connection to PC for motion 
programming and execution. 

• IR handheld remote to execute user-created program 
motions. 

• Powered by five AA batteries. 

• Spare ports available for installation of sensors for 
autonomous operation. 

For further information, please contact: 



RoboBrothers, Inc. 



Website: www.robobrothers.com 



24 SERVO 10.2012 



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KS BRIEF 




KINECT WITH ADAM 

Make Ahlers — a student of neurobiology in Germany — has built 
a humanoid robot torso called Adam (Advanced Dual Arm Manipulator), 
or A I for short. Although the project is still somewhat early in 
development, the hardware side of things has been in the works for 
around two years. 

Adam's arms have five degrees of freedom actuated by robolink 
joints from Igus — a German robotics company.The robolink joints have 
both pivot and rotation - ideal for building robot arms - but they use 
external cables for their rotation (much like a pulley; one for clockwise 
and another for counterclockwise rotation). The resulting bundle of 
cables had to be routed to planetary gear motors inside the torso, and 
Ahlers had to build a motor controller to read out the position 
encoders in the joints in order to drive the motors with position 
control. 

For the hands, he went with FESTO's flexible FinGrippers which use 
a simple, yet surprisingly effective design. FESTO is also a German 
company, famous for its biologically-inspired robots and the FinGrippers 
are no exception. Using just one motor, three fingers 
pinch together in unison and will naturally conform to 
roundish objects of varying size. Finally, Adam's head 
(sitting on a two DOF neck) has a Microsoft Kinect 
sensor and two Logitech QuickCam Pro 9000 cameras. 
A speaker provides for speech synthesis and an LCD 
panel features animated "lips." For now,Adam remains 
an impressive work-in-progress. 




NOW THEY'RE (NOODLE) COOKIN' 

Little by little, robotic chefs are taking over China. One of the latest " A imS* 

is Chef Cui who specializes in noodle cutting. Designed by Cui Runquan,this chefbot is being mass-produced with a reasonable 
price tag of $1,500. We call that reasonable since hiring a chef could cost $4,700 yearly. Runquan says that the upcoming human 
generation isn't really into a career as a cook, so with about 3,000 already sold he expects these robotic counterparts will pick 
up the slack. 

The Chefbots can "hand" slice noodles into a pot of boiling water. According to one human, "The robot chef can slice 
noodles better than human chefs." 



26 SERVO 10.2012 



IN BR^ 




WEE0OT FOR WEE ONES 

This is aWeeBot, and it's one of the very rare times it's okay 
to combine robots with babies.That's because aWeeBot is 
basically a way of turning a real baby into an unstoppable fusion of 
biology and engineering. 

Babies (as you may have noticed if you own one) like to get 
into all sorts of mischief, and studies show that exploring and 
interacting with the world is important for cognitive development. 
Babies who can't move around as well may not develop at the 
same rate as babies who can, which is why researchers from Ithaca 
College in New York are working on a way to fuse babies with 
robots to give mobility to all babies — even those with conditions 
that may delay independent mobility, like Down syndrome, spina bifida, or cerebral palsy. 

WeeBots are built with Adept MobileRobots Pioneer P3-DX bases. On top of the bases are Nintendo Wii balance boards 
which are rectangular platforms with load sensors at the corners. A commercial infant seat is placed on top of the balance 
board, and the robot can then be calibrated to move in whichever direction the baby leans. 

To test the WeeBots, researchers borrowed five infants, ranging in age from six months to nine months. Each infant was 
given five training sessions on the robot using a toy as bait, and by the end of those sessions, the babies were reliably able to 
control the WeeBot in goal-directed movement during periods of free play. You might think that a six month old baby wouldn't 
necessarily have the facility to control a robot like this, but they catch on surprisingly quickly. All of the babies in the study 
were developing typically for their age; none of them had the ability to crawl, so the robots were their only means of 
transportation. 

This was just a pilot study to make sure that the WeeBot worked, but recently published continuing research has also tried 
using WeeBots with infants with mobility disorders. It's turning out to 
be difficult for some babies to sit up enough to control the WeeBot by I 

leaning, but in at least one case, a 15 month old boy with cerebral palsy 
was able to learn to control aWeeBot — after which he started to 
develop crawling skills on his own. 



AIRarm YOURSELF 

Here's a fully controllable robot arm that can be inflated and 
deflated like a balloon. 

TheAIRarm is lightweight, inexpensive, and stows compactly. It's 
inflated and deflated with an onboard pump, and uses actuators and 
strings to move its joints without embedded motors. While regular 
PackBot three-link arms are between 15 and 20 pounds, the AIRarm 
system only weighs about a tenth of that — a fact that would be 
appreciated by the soldiers that have to carry these robots around. 

Despite its light weight,AIRarm is no slouch and can lift up to five 
pounds or possibly more, depending on how much it's inflated. By 
varying the level of inflation, it's also possible to vary the level of 
compliance of the arm; this makes the arm a little bit flexible when you 
need it to be which, in turn, makes it safer and more durable. Since it's 
mostly made of fabric and string, it's wicked cheap, at least compared to 
a conventional arm. 




SERVO 10.2012 27 



GET STOMPY 

This is Stompy — a giant hexapod that you can ride in. (How 
awesome is that!?) 

Stompy is the brainrobot of Artisian's Asylum, a hackerspace out 
in Boston. This is actually a serious undertaking. The guys behind it are 
experienced roboticists from places like Boston Dynamics, Barrett, 
and DEKA.The robot will be powered by a 135 horsepower engine 
driving a whole bunch of hydraulics, and while it's largely designed to 
stomp around in an exhibitory manner, the team has big plans fot it. 

The robot isn't just being built for fun. It has practical purposes, 
as well. With six force-sensitive legs and a ground clearance of six 
feet, the robot will be able to walk over broken terrain that varies 
from mountainous areas, to rubble piles, to water up to seven or eight 

feet deep — 





everywhere existing ground vehicles can't go. Not only that, while 
navigating such terrain Stompy could carry 1,000 pounds at 2-3 mph,and 
up to 4,000 pounds at I mph.This is important in disaster areas because 
Stompy (and the technology it represents) could easily reach people who 
can't be reached by other means. 

So how big is big? Check out the photo. 

Yep. That's a person! A really tall person named Matt. 




LEAPS OF FAITH 

Roboticists at the Harbin Institute of Technology in 
China have managed to make a robotic insect that — in 
addition to walking on water — can also jump. Modeled 
after a water strider, the legs of this robot are made of a a 
porous, water-repellent nickel foam. The concept is that if 
you spread the weight of the robot out enough, the 
surface tension of the water can support it. This is a tall 
order for a robot this large. Weighing in at I I grams, this 
porker is over a thousand times the mass of its biological 
inspiration. 

To get the robot to jump, a separate set of legs was added, bringing the total to five. By using these actuating legs to push 
against the surface of the water, the robot was able to make leaps 14 centimeters high and 35 centimeters long, taking off at 
nearly 65 kph which is impressive for such a little guy. Robots like these could skim across lakes and other bodies of water to 
monitor water quality or act as tiny spies. 

Cool tidbits herein provided by www.botjunkie.com, www.robotsnob.com, www.plasticpals.com, http://www.robots-dreams.com/, and other places. 



28 SERVO 10.2012 




Twins Geoffrey Howe 
(left) and Michael 
Howe flank their 
new invention — 
a fire-fighting robot 
known as the 
Thermite. 



THERMITE TAKES THE HEAT 

Brothers Geoffrey and Michael Howe (who 
build robots for the military) decided there was a 
need for a bot that fights fires.The Thermite weighs 
1 ,400 pounds, stands about four feet tall, and moves 
on a track (for now). Running on diesel, it has video 
and infrared cameras so it can be remotely 
operated. 

Geoffrey calls it the "Swiss Army knife of 
robotic responses" since it can operate with various 
attachments like a hydraulic arm for saving humans. 
After spending a couple of years testing the firebot, 
the twins have already sold a few of them. 

The Thermite has been described as a rugged 
powerhouse of a vehicle. At 34 inches wide, Michael 
says it's small enough to get into a burning room, yet 
powerful and well-equipped enough to extinguish 
fires when it gets there. 

For example, a hydraulic arm can be bolted on 
with the strength to pull a human out of a burning 
building, among other things. "It can move a 55 
gallon drum full of chemicals away from a fire," 
Geoffrey comments. "It can do all sorts of things 
that you may need done in an emergency situation 
including turning valves, cutting wires, or cutting 
rope." 

The Thermite has been tested in a number of 
situations, including a scenario known as a bleve, 
"which is a boiling liquid expanding vapor explosion," 
Michael says. "This happens when a tanker truck 
rolls over, and you can see on the news a big fire 
shooting out of a tanker, and eventually it explodes. 
A lot of firefighters lose their lives trying to get in 
there and extinguish that. This can go in there. Also 
fuel farms — where they keep all the fuel — they 
catch on fire, and it's just too hot to get in there. 
Send a robot in. I believe this technology (in five to 
10 years) will be standard operating procedure for 
every fire department, to have some sort of robotic 
solution." 




NICE PRICED MITT 

As part of DARPA's ARM program, Sandia has partnered 
with Stanford University to create a dexterous robot hand on 
the cheap. 

As Sandia puts it, "The Sandia Hand addresses challenges that 
have prevented widespread adoption of other robotic hands such 
as cost, durability, dexterity, and modularity." You can attach tools 
like screwdrivers or flashlights (or laser cannons), and the 
modular design also makes the hand durable, since the fingers 
will just fall off if something smacks into them. As principal 
investigator Curt Salisbury explains, "If a finger pops off, the 
robot can actually pick it up with the remaining fingers, move it 
into position, and resocket the finger by itself." Also, the "skin" of 
the hand is designed to mimic the flexibility of human tissue, 
providing some shock absorption and allowing the hand to more 
firmly grasp objects. 

This is all really cool stuff, but the cost is where the hand 
really comes through. In low volume production, the Sandia Hand 
should only cost about $10,000 total. (Fingers included.) For the 
record, Sandia's press information says that's about 90% less than 
other commercially available robot hands with similar 
independently actuated degrees of freedom. 

The operator controls the robot with a glove, and the lifelike 
design allows even first-time users to manipulate the robot easily. 

Using Sandia's robotic hand to disable lEDs (improvised 
explosive devices) might help lead investigators to the bomb 
makers themselves. Often, bombs are disarmed simply by blowing 
them up. While effective, that destroys evidence and presents a 
challenge to investigators trying to catch the bomb maker. A 
robotic hand that can handle the delicate disarming operation 
while preserving the evidence could lead to more arrests and 
fewer bombs. 



SERVO 10.2012 29 



DOUBLE TROUBLE 

Doing robotic telepresence can be tricky. It's one of those 
things that sounds good on paper, but when it comes to getting 
people to plunk down a pile of cash for the hardware, going 
commercial with the concept has proven to be more or less 
impossible outside of some very specific circumstances. Double 
Robotics — a startup out of Y Combinator — is taking a shot at 
the telepresence space with a slick new iPad-based platform called 
Double. 

When we say it's "iPad-based," it's literal. Double is pretty much 
a mobile base for an iPad.You can log into the iPad from any 
computer or iOS device, and drive the robot around while 
streaming two-way audio and video. Double lets you talk to people, 
go sightseeing, or do whatever else you want while remotely 
inhabiting the body of a robot. The iPad can be extended vertically 
from three and a half to five feet to maintain eye level with people 
sitting or standing, and the Segway-style base uses high efficiency 
motors to zip around for up to eight hours on a charge. It has a 
futuristic, minimalist design, and it has a low preorder price of 
$2,000 (iPad sold separately). 




Double arrives fully functional as soon as you 
open the box — just insert your iPad. Touch the 
power switch to activate Double's self-balancing 
sensors (keeping itself upright). At only 15 pounds 
(7 kg), it's easy to move by hand and won't damage 
furniture. 

Setting up Double on your iPad is as easy as 
downloading an app.The same app is used for the 
driver's iPad and the robot's iPad. Once you create 
an account, your driver's iPad will display all of your 
Doubles anywhere in the world from one screen. 

Connect to Double by tapping its icon, which 
will initiate an interactive video call. During the call, 
touch the screen anywhere to engage the driving 
controls. Slide your thumb to drive and turn. 
Additional controls adjust your height remotely, 
park yourself with the kickstands, and more. 

You can drive Double from an iPad, iPhone, 
iPod touch, or desktop web browser. 



47"-«0'* 1119-152 cm) _ 


n 

Double 


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KICKSTANDS 




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30 SERVO 10.2012 



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I 



Featured This Month: 

32 BUILD REPORT: 

Testing the Prototype: 
Klazo — My 1 lb Drumbot 
From Kitbots.com 

by Michael Jeffries 

34 Upcoming Events 



35 Clash of the Bots 3 

by Andrea Suarez 

38 The History of Robot 
Combat: Robot Battles 
at Dragon*Con 

by Morgan Berry 



40 CARTOON 



www.servomagazine.com/ 

index.php?/magazine/article/ 

october2012 CombatZone 



BUILD REPORT 



Testing the Prototype: Klazo — 
My 1 lb Drumbot From Kitbots.com 



by Michael Jeffries 



I recently built and tested one of 
the prototype 1 lb drumbot kits 
from Kitbots.com as part of the 
development process, prior to the 
kit moving to production. At the 
beginning of the build, I received 
the fully assembled chassis along 
with four kit gearmotors that 



formed the basis of this build. 
The chassis is a combination of 
UHMW plastic, aluminum, and 
the Kitbots product Nutstrip — 
much like the Weta and Trilobite 
kits. The design of the chassis 
closely resembles Weta, however, 
there is an important difference in 




M SERVO 10.2012 




FIGURE 3. Partially manufactured drum showing 

motor positioning. 



FIGURE 2. View of the internal layout of the chassis 
showing drive motors and TinyESCs. 



the weapon system. Unlike with 
Weta, the brushless motor that 
powers the weapon is contained 
within the drum. 

The first priority of the build was 
to get the electrical system working 
to allow for testing of the prototype 
gearboxes. I started with the drive 
portion of the electrical system 



which meant the installation of 
FingerTech Robotics TinyESCs, a 
Rhino 460 7.4V Li-Po battery, 
Hobbyking R410 OrangeRX, and a 
small power switch. For this portion 
of the build, the power switch was 
left floating. 

Once the initial portion of the 
wiring was completed, I spent some 



time testing the drive system. After 
stalling one of the gearboxes, I 
noticed that the side of the drive 
system was not functioning at full 
capability. I dismantled the gearbox 
and found that some of the 
gearteeth were damaged. As part of 
this process, I noticed that the 
gearboxes were visually identical to 




SERVO 10.2012 33 




the FingerTech 22:1 Silver Spark 
gearboxes, though they were of 
lower quality. I swapped out the 
prototype gearboxes for the Silver 
Spark versions and have yet to have 
an issue with them. 

I then moved on to the 
creation of the drum for Klazo. The 
drum is made from a 1 " ID, 1 .5" 
OD 6061 aluminum tube. I used 
my small lathe to bore out one side 



EVENTS 



Upcoming Events 



WERC Franklin M I 4 ■TlJ 
Institute I i I Halt 

9ni9vA/illho 



IERC Franklin 
Institute 
2012 will be 

presented by the North East Robotics Club in 
Philadelphia, PA on October 6th. 
www.nerc.us 



Iecha- 
Mayhem 
2012 will be 
presented by the 
Chicago Robotic 
Combat 
Association in 
Cleveland, OH 

October 13th and 14th. www.theCRCA.org 
SV 




of the tube to fit the weapon 
motor, then turned down the 
surface of the tube to reduce some 
weight and minimize the imbalance 
of the drum that would come from 
the lack of precision my lathe 
allows. After turning the drum to 
size, I drilled holes through both 
walls of the drum that were sized 
for a 10-24 tap. The holes were 
quickly tapped and the screw-based 
teeth were attached to 
the drum. Once this 
was completed, the 
motor was glued into 
the drum with Goop (a 
silicone based 
adhesive). In 
preparation for the 
initial test spin, I 
mounted the power 
switch to the bottom 
armor plate to allow 
operation of the robot 
without exposed 
electronics. 

In testing, the 
drum wasn't perfectly 
balanced but was close 
enough that the robot 
could drive reasonably 
well with the weapon 
at full speed. The final 
step before its debut 
at Clash of the Bots 3 
was the addition of 
two 1/16" titanium 
"wedgelets" that would 



increase the chances of it getting 
under an opponent prior to impact. 

Klazo went 2-2 at Clash of the 
Bots 3, and survived a great deal of 
abuse across all of the matches. 
During the event, Klazo faced Saifu 
— the prototype kit built by Pete 
Smith. The match lasted a full two 
minutes and went in favor of 
Klazo. The deciding factor in the 
match appeared to be a gearbox 
failure on Saifu. The relevant 
differences between the two 
robots were the change in 
gearboxes to the FingerTech Silver 
Sparks and the use of lite flite 
wheels on Klazo instead of the 
hard plastic wheels that Saifu used. 

After the event, I decided to 
make a more balanced and heavier 
drum since Klazo was well below 
the weight limit. The new drum has 
eight 10-24 flat head screws for 
teeth instead of the four used on 
the initial drum and has a slightly 
larger diameter. Outside of that 
modification, Klazo is ready for the 
next event (which was the Robot 
Micro Battles in Atlanta, GA during 
Dragon*Con). 

Overall, I am happy with the 
durability of the kit and relative 
ease of construction. The most 
difficult portion of the build was 
making the drum. However, I 
suspect there will be at least one 
stock option available upon the 
release of the kit. 



Clash of the B^ts 3 




Iotorama Carolina Combat 
Robotics hosted its third Clash 
of the Bots on July 14 at the Schiele 
Museum of Natural History. Builders 
traveled to Gastonia, NC from across 
the country with almost 40 robots in 
three combat weight classes (Flea, 
Ant, and Beetle). As we approached 
the venue, the first thing that caught 
my eye was the "Clash of the Bots 
TODAY" on the museum's LED sign 
near the main road. 

We were the first competitors to 
arrive at the event, and the venue 
had a sort of calm-before-the-storm 
feeling. All the pit tables were 
perfectly organized with our 
competitor packets nicely laid out. 
The arena sat in the dark, ready for 
action. Chuck Butler recalls: "Four 
years ago, I received a message from 
Christie at the Schiele Museum in 
Gastonia looking for someone that 
could do a robot presentation for a 
group of 100 Girl Scouts. We took 
on the task, and the girls were 
surprisingly very interested in the 



• by Andrea Suarez 

destruction, especially when it 
involved a Barbie doll vs. a combat 
robot. We had been looking for a 
suitable venue and when the 
museum decided they would like to 
try a robot day it was a perfect fit, 
and Clash of the Bots was born with 
an average of over 500 visitors at 
each event." 

As visitors entered the Schiele 
Museum, you could instantly hear 
the sounds of battle coming from 
the competition area, attracting 
crowds of spectators to the arena. 

Ram Robotics drove from Florida 
to North Carolina to compete their 
fleet of robots across all the weight 
classes, including two new robots: 
iKid (Flea), and Calamity Kid (Ant). 
David Liaw flew from California for 
the event, but his robots were lost at 
the airport! The event started with a 
builder's meeting where Chuck 
welcomed competitors and 
explained the rules for the day. 

Even without arena hazards, 
every two minute match provided a 




1 ^ I1UI 


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does some 

last minute 

weight 

adjustments 

to his new 

Fleaweight . ►^~f F 

bot, iKid. ^ ™* 


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show of sparks and flying robots. It 
was all captured in high speed at 
300 frames per second by Robert 
Woodhead and provided to the 
competitors free of charge. Robert 
also provided free DVDs of past 
events to the competitors and 
spectators. 

FLEAWEIGHT CLASS: Seven 
robots made up the Fleaweight 
bracket. Caterpiller, last year's 
winner, returned with its massive 
servo-powered lifting plow that was 
sliced up by Paul Grata's Pissed Off 
Unicorn as both robots went 
spinning across the arena in a first 
round match-up. Busted Nuts 
Robotics brought five of the 
Fleaweight bots, which provided for 
plenty of competition among the 
teammates. 

Dirty Sanchez's two vertical discs 
met seemingly weightless one- 
wheeled melty-brain Berzerker for 
some big air time almost every hit. 
Dirty Sanchez even did four and a 
half flips through the air on a single 




FIGURE 3. The Clash of the Bots staff. 
(Photo by Yong Ye.) 



FIGURE 4. Algos 
vs. Saifu. 




FIGURE 6. Caterpillar vs. Pissed Off Unicorn. 



SERVO 10.2012 35 



blow. Duke Robotics 1 Trash used its 
vertical oversized beater to take the 
horizontal disc off Invertigo in the 
first round. In the semi-finals, Pissed 
Off Unicorn easily took out both of 
Invertigo's wheels, advancing to the 
finals to fight an undefeated Thrash. 
Pissed Off Unicorn used its eight 
inch spinning weapon to defeat 
Thrash twice for the Fleaweight title. 

ANTWEIGHT CLASS: Thirteen 
robots battled it out in the 
Antweight division. Early in the 
bracket, Poco Tambor sent Klazo 
high in the air hit after hit, almost 
getting Klazo stuck between the 
arena barrier and the wall as it 
bounced off the arena. Caleb 
Boothe from Duke Robotics 
competed with his first robot, a 
nicely machined full-body spinner 
Shaka Zulu, and received a tough 
first match-up against Jamison Go's 
well known DDT. 

Both robots took big hits, until 




FIGURE 10. 
OpenRobotix's 
Chobham 2.0, 
winner of 
Coolest Robot. 




FIGURE 13. DDT vs. Algos. 




Shaka Zulu flipped upside down and 
danced circles around DDT while it 
tried to self-right. DDT's luck was 
running short, however, as he lost 
his next match against Poco Tambor 
and then lost to Algos. Saifu, built 
by Pete Smith of Kitbots, did well in 
the first round with its reversible 
direct drive brushless drum weapon. 
After winning its match against 
Algos, Saifu was sent to the loser's 
bracket by Capricant and was then 
eliminated by Klazo, which is based 
off the same kit as Saifu. 

Last year's winner, Gilbert from 
Team MH Robotics, returned to 
reclaim his title at Clash of the Bots 
3. After beating Ting Tang and Blue 
Devil, Gilbert lost its match against 
Poco Tambor and fought its way 
through the loser's bracket. 
Defeating WhipperSnapper and 
Calamity Kid secured Gilbert a spot 
in the finals. 



FIGURE 8. DDT vs. 
Shaka Zulu. 




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FIGURE 11. 
.Bot hockey 
draws a 

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Capricant stayed in the winner's 
bracket throughout the event, 
sending Poco Tambor to the loser's 
bracket late in the competition to 
battle Gilbert in the semi-finals. In 
the final match, Poco Tambor sent 
Capricant spinning in the air until 
Capricant lost power. Poco Tambor 
ended the Antweight matches with 
a gyro victory dance for the crowd. 

BEETLEWEIGHT CLASS: Twelve 
3 lb competitors put on a great 
show for the crowd. The first match 
paired Grande Tambor vs. 
OpenRobotix's TomZax — both with 
powerful vertical weapons. Eight 
year old Thomas Parrish behind the 
controls of TomZax tried to use his 
saw blade wheels to outdrive 
Grande Tambor, but Grand Tambor 
won the match after several big hits. 

Two Florida teams took 
the stage next, as Voodoo 
Magic's titanium vertical disc cut 





FIGURE 15. 
Pissed Off 
Unicorn vs. 
Thrash. 




36 SERVO 10.2012 



horizontal-bar-spinner Steve's power 
switch early in the match. 

Jamison Go brought a powerful 
new drum bot to this event, 
Dominant Mode, which delivered 
some devastating hits against 
Rarmvac and Weta God of Ugly 
Things (last year's champion). In the 
latter match, Dominant Mode was 
flipped upside down, allowing Weta 
to get some good hits against 
Dominant Mode's titanium armor. All 
the kids took a step back from the 
arena as the shower of bright sparks 
hit the arena wall. Dominant Mode 
was eventually able to self right, and 
after two minutes of constant 
contact between the bots, the judges 
deemed Dominant Mode the winner. 

DeJa Voodoo and Grande 
Tambor took the stage next for a 
forceful match between these two 



drum bots that ended with DeJa 
Voodoo sending Grande Tambor into 
the ceiling. In the rematch between 
these two bots later in the bracket, 
Grande Tambor landed on the floor 
with so much force that both drive 
shafts sheared off, rendering Grande 
Tambor immobile. 

Shame Spiral worked its way 
through the winner's bracket 
undefeated to meet DeJa Voodoo in 
the finals. After a serious driving skill 
show from both competitors, DeJa 
Voodoo's drum couldn't penetrate 
Shame Spiral's wedge. The match 
ended with DeJa Voodoo wedged 
between the arena barrier and the 
outside wall, and the judges named 
Shame Spiral the Beetleweight 
champion. 

BOT HOCKEY: The bot hockey 
division drew a lot of attention as 



TABLE 1 CLASH OF THE BOTS 3 WINNERS. 


1st: 


Fleaweight 

Pissed Off Unicorn - 
Busted Nuts Robotics 


Antweight 

Poco Tambor - 
Team Pneusance 


Beetleweight 

Shame Spiral - 
MH Robotics 


2nd: 


Thrash - 

Busted Nuts Robotics 


Capricant- 
Ram Robotics 


DeJa Voodoo - 
Busted Nuts Robotics 


3rd: 


In vertigo - 

Busted Nuts Robotics 


Gilbert - 
MH Robotics 


Grande Tambor - 
Team Pneusance 


Bot 
Hockey: 


Team Meatheads 


Team Scotch Pies 


Team Pneusance 


Coolest Robot: Chobham 2,0 


- OpenRobotix 





FIGURE 17. DeJa Voodoo 
gets wedged in the arena 
vs. Shame Spiral. 




FIGURE 20. Grande Tambor vs. 
^The Liberator. Photo by Yong Ye. 



each team of three robots tried to 
get the puck into the opponent's 
goal. First place went to Team 
Meatheads which consisted of 
Thomas Kenny from Team 
Meatheads, David Liaw of Team Ice, 
and Mike Jeffries of Team Near 
Chaos. Team Scotch Pies came in 
second place, and Team Pneusance 
took third place. 

The "Coolest Robot" winner was 
OpenRobotix's Beetleweight 
Chobham 2.0, who received a Kitbots 
kit for its unique look. The other 
winners received prizes from the 
event sponsors: Kitbots, FingerTech 
Robotics, and SERVO Magazine. 
Chuck Butler would like to extend a 
"thank you" to the Schiele Museum 
for hosting the event and providing 
lunch to all the competitors, to all the 
event sponsors and volunteers that 
made the event a success, and to 
Robert Woodhead for recording the 
event in high speed. It was a great 
event with high quality robots, and I 
am already looking forward to Clash 
of the Bots 4! 




FIGURE 



RE 16. DDT 
vs. Poco Tambor. 




FIGURE 19. Algos vs. Calamity Kid — both 
new bots to this event. Photo by Yong Ye. 



FIGURE 21. Shame Spiral vs. DeJa Voodoo. 
Photo by Yong Ye. 




v*^ 



FIGURE 22. Poco Tambor vs. Gilbert. 
Photo by Yong Ye. 



SERVO 10.2012 37 



The History of 
Rob#t Combat 



Robot Battles at Dragon*Con 



Robot Battles at Dragon*Con 
in Atlanta, GA is one of the 
oldest robot combat events. In 
1991 (for perspective, that's the 
same year that the World Wide 
Web was launched), a few years 
after the Denver Mad Scientists 
Society created Critter Crunch at 
MileHiCon in Denver (as discussed 
in the first History of Robot 
Combat article in the January 
2012 issue), Kelly Lockhart was 
inspired to create a combat 
competition of his own. He used 
Critter Crunch as his model and 
hosted a simple event which soon 
became a mainstay of the robot 
combat world. 

Lockhart was kind enough to 
tell the story of the early Robot 
Battle events: 

"The genesis of Robot Battles 
started in Denver, CO back in 
1987 when a group of 
engineering types created the 
'Denver Mad Scientists Society' 
and staged a small robotics- 
oriented competition at a local 



• by Morgan Berry 

science fiction convention. The 
'Critter Crunch' event caught on 
(and is still going strong to this 
day), and word spread of the cool 
new idea. 

"Come 1991, the organizers 
of the Dragon*Con convention in 
Atlanta approached me about 
staging something similar. So, I 
got a copy of the Critter Crunch 
rules from the Mad Scientists (of 
which I later became a member), 
and figured out how to stage it 
simply and with as little fuss and 
muss as possible. 

"My original vision is the one I 
still follow to this day: Have fun. I 
strive for everyone to have as 
much fun as possible — the 
builders, the drivers, and most of 
all, the audience. 

"This vision is, I believe, what 
has kept Robot Battles going 
strong into our third decade. 
Because we never got bogged 
down by internal or external 
politics, we never got into money 
conflicts, and we have always 



worked together to keep 
everything as entertaining as 
possible, we've survived when so 
many other events and 
competitions have fallen by the 
wayside. 

"The first event had two 
robots entered. One was from a 
team from Georgia Tech, the 
other was built and driven by a 
student from the University of 
Georgia. Needless to say, there 
was a built-in rivalry from the very 
start. We were set up in the 
basement level of the Atlanta 
Hilton which at that time was bare 
concrete. We didn't have a stage, 
a PA system, lighting, video 
screens, or any of the things we 
take for granted today. What we 
did have was nearly 300 people 
surrounding the combat area 
(which was marked out with duct 
tape), cheering on the eventual 
winner ... the driver from UGA. 

"The second year, we had 
seven competitors. Within five 
years, we had over 20 bots 




FIGURES 1 and 2. In these shots of the rumble at the end of Robot Battles at Dragon*Con last year, 
you can see the raised platform arena that is unique to Robot Battles. 



» SERVO 10.2012 



entered, had the use of a large 
ballroom to handle the SRO 
crowds, lights, sound system, the 
whole nine yards. It was obvious 
that we had hit on something. 

"As we went along, we've 
changed weight classes, adapted to 
changing technology, moved to 
ever large venues, and spread out 
to other conventions around the 
country (including back in Denver 
for several years). Currently, we 
hold events in Chattanooga, 
Nashville, as well as Atlanta, and 
may be returning to Orlando after a 
two year absence. 

"But even with all the changes 
and growth, we've stayed as true to 
the spirit of the original rules and 
vision as possible." 

Aside from its long history, 
Robot Battles at Dragon*Con is 
unique in other ways. Unlike most 
robot combat events that take 
place in an enclosed arena, the 
bots at Robot Battles compete in 
an open air arena. 

As a result, the competition is 
less about "the high energy whirrrrr- 
bang aspects of conventional 
tournaments" and more about 
"strategy, driving, and at times, 
straight up weirdness," competitor 



Charles Guan said. This all makes 
for a very good spectator sport — a 
fact that the competitors happily 
embrace. "People regularly come up 
on stage in costume, or the robots 
look ludicrous themselves. My 
favorite in recent years was a very 
well driven and solid wedge robot 
that was coated in brown fur and 
made to look like a beaver." 

The unique setup also leads to 
technological creativity. "There have 
been robots in the past which have 
automatic opponent-seeking 
sensors, as well as ones which 
could translate as they were 
spinning the entire robot frame by 
varying motor speed periodically. 

You get robots made from 
materials that don't get used 
normally in arena combat like 
hardware store plastic window 
glazing and aluminum tubes 
because they're just not durable 
enough or hard enough," Guan 
said. 

STEM Education is one of the 
most important issues in the 
technology world today. The folks 
at Robot Battles are doing their 
part to get the younger generation 
involved. 

"Our audiences range in age 



from very young (under 1 0) to folks 
that were around in the day when 
even the concept of robots was 
pure science fiction. And it's been 
that way from the very beginning," 
Lockhart says. "From the very first 
years, we have always encouraged 
young people to get involved. Our 
youngest tournament winner was 
eight years old, and he wasn't the 
only single digit age winner over 
the years. Some of our most 
popular and successful builders 
started when they were in their 
early teens, some even younger ... 
the other builders have always 
gone out of their way to teach and 
encourage the new builders." 

Long time competitor Guan 
echoed Lockhart's sentiment. "The 
most well-known story of new 
builder triumph is an eight year old 
boy who built a plywood wedge 
shell around an otherwise 
unmodified R/C monster truck, and 
went on to defeat an entry from 
Georgia Tech." 

Guan is himself an example of 
the youth presence at Robot Battles 
— this student has participated in 
the event for many years. 

"Robot Battles has become one 
of the more popular events at 



ADVICE AND TIPS FROM A COMBAT VETERAN 

Charles Guan offers this advice to people considering competing in Robot Battles (or any robot 
combat event) for the first time: 

"I encourage everyone who is thinking of entering a robot or interested in getting their feet wet in 
engineering hobbies to come and watch a competition. Once you experience the competition firsthand 
and talk to the builders and see the robots, you are far more likely to pick up and do it. 

Viewing robot competitions over the Internet or hearing about it from friends, people often get 
discouraged because they think it's above their level or their ability. There is no place where this is more 
untrue than at a Robot Battles event — many winners in the past have been children or teens, some with 
their first and second robots. Once you finish your first contraption, I sincerely recommend driving it as 
often as you can. Get to know how your machine moves, because having a cool weapon is only half of the 
equation — keeping your robot moving and avoiding (or attacking) the opponent is the other. 

Finally, when you get to the event, don't stress out. Relax, talk to fellow builders, introduce yourself, 
and spend some time practicing on the stage before the match starts. Remember that you are being 
watched by the audience just as much as the robot is. Some people get stage fright and stress out during 
the match, and that leads to poor performance and often hurt prides. 

And no matter what, even if you don't win — especially if you don't win — always think of how you can 
learn from the experience, whether it is a new robot design, knowing what to fix for next time, or just from 
picking other builder's brains about how they accomplished something. " 



SERVO 10.2012 39 



Dragon*Con. We have to hold 
the event over two days to 
accommodate the number of 
entries in the four weight classes 
(one, three, 12, and 30 pounds), 
in fact. 

There are — on average — 1 0- 
20 robots entered in each weight 
class. And crowds range from 500+ 
for the Microbattles — which could 
easily double in size given a larger 
ballroom — to over 2,500 for the 
main event on Monday in the 



second largest ballroom available at 
the Hyatt Regency," Lockhart 
commented. 

When asked what the future 
held for Robot Battles, Lockhart 
had this to say: "My vision of the 
future of Robot Battles is the same 
as it has always been: Keep having 
fun. There are always small 
changes to venues, adaptation of 
new technologies, changes in 
marketing and publicity, and over 
time some builders move on while 



new faces appear. But as long as 
we stick to the core philosophy to 
have fun for everyone, I think we'll 
keep being successful. I started 
Robot Battles when I was 22 years 
old. Twenty-two years later, it's still 
one of the most fun things I get to 
do every year, and I see no reason 
why I can't keep doing this for 
another two decades, or more. 
'Two bots enter, one bot leaves ... 
often in pieces.' That is what I call 
fun." SV 





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FIGURES 3 and 4. These bots are an example of the kind of creative and lighthearted approach 
the builders at Dragon*Con take to Robot Battles. 



1e!ty Brains ^ K*™ Bemj 

This month on Antique Bot show: Name that artifact! 



A 





Jf& AsUVtltsJ^ 



„9$P»M 4y&9*HUV U9AUQ 0AJ9& n J 



40 SERVO 10.2012 



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Give Yourself 
a Wedgie! 



by Zachary Lytle 




As a four-time RoboGames champion, I am frequently asked how to get started 
in combat robotics. Personally, I always recommend building a wedge for your 
first robot because you don't want to start off with anything too complicated. 
Wedges are durable and easy to repair, which are the two most important 
qualities in your first robot. Plus, let's not forget that the current RoboGames 
heavyweight champion Original Sin is basically a gigantic wedge robot. In this 
article, I will show you how to build a wedge platform from scratch using 
common household tools. The boxes are locked, the lights are up, and the arena 
is waiting for you, so let's get started! 



The tools and parts you'll need to construct 
your wedge are listed on the next page. The 
total cost of these parts should be around 
$320. Starting with the appropriate materials 
can save you a lot of trouble down the road. 
Let's begin. 

42 SERVO 10.2012 



BUILDER 
TIP: Always 
weigh your 
parts to see 
how much 
poundage 
you have to 
work with. 




on 




The tools you'll need are: 

Hand drill 

Soldering iron with solder 

Six inch caliper 

Lighter 

English Allen wrench set 

1/8" drill 

Tin steps 

Wire stripper 

Sharpie™ pen 

Fine-grained file 

2x3 inch clamps 

Bottle of CA glue 
Optional: 

Dremel with cutoff wheel 

Drill press 

Five pound scale 



The parts you'll need are: 
6" x 6" titanium sheet 

2x FingerTech Robotics 22-1 Silver Spark motors 
2x FingerTech tinyESC v2 motor controllers 
2x Lite Flite wheels, two inches in diameter 
2x FingerTech Lite Hubs 
JST connector (female) 
DX 5E radio system 

Rhino 460 mAh 2S 7.4V Li-Poly pack and charger 
6" x 6" polycarbonate sheet .040 inches thick 
25x 4-40 button head screws 1/4 inch in length 
2x BaneBots motor mounts 

Most of the parts can be found at 
FingerTechRobotics.com; the metal and screws 

can be found at www.mcmaster.com; 
and the motor mounts are from Banebots.com. 



MAKING THE 
TOP PLATE 

This is the primary armor 
and structure for the entire robot. 
All of your components will be 
mounted to this single piece of 
metal. Some might call this 
"putting all your eggs in one 
basket," but I can tell you from 
experience this is the best 
approach. 

By putting all your weight into 
a singular piece of metal, it allows 
you to build the frame and armor 
on top of each other, and this 
makes them inseparable. Designs 
that make the armor a removable 
piece typically get it ripped off 
and destroyed. 



middle, and scribe two additional lines 1-1/4 inches from the left and right hand 
along the horizontal line. When you are done, you will have seven crosshairs. 




STEP1: LAYING THE 
HOLE PATTERNS 

Lay out the bolt hole patterns 
with the caliper. By locking the caliper 
at the desired dimension, you can use 
the caliper as a ruler to scribe lines. 

Set the caliper at 1/8 inch and 
scribe a line down each side of the 
titanium sheet. 

Set the caliper at 1/4 inch and 
scribe two additional lines, measuring 
from the top and intersecting your 
first two 1/8 inch lines. This will make 
a cross hair you will use to line up 
the drill. 

Scribe a second set of small lines, 
3/4 inches down from the top. 

Next, scribe a line two inches off 
the bottom edge all the way across. 
Then, scribe a line directly in the 
side. This will create three cross hairs 



SERVO 10.2012 43 



STEP 2: MARKING THE HOLES 

Be sure to take your time on this 
step. After making the seven scribed 
crosshairs, take the punch and the 
hammer and create a small divot over 
each cross hair. These small divots will 
guide the drill through the material. 
Hard metals — like grade 5 titanium — 
typically cause drills to "walk" off the 
desired location. By scribing and 
marking holes with the punch, you will 
gain a much higher level of accuracy 
with the drill. 




r t 


nBL ^Hi^B 





STEP 3: DRILLING THE HOLES 

The last step for the titanium is to 
drill it. Put your hand drill on a low 
speed at approximately 500 rpm, and 
make sure the 1/8 inch bit is securely 
locked in the chuck. Place a block of 
wood underneath the titanium plate. 
Take your spray can of WD-40 and 
spray the drill and sheet before you 
start drilling. Place the drill in the 
divot and get lined up, straight up 
and down. Apply moderate pressure 
while drilling. 



STEP 4: CHECKING 

YOUR HOLES 

Hold the motor mount up to the 
titanium plate and visually check to be 
sure you can see both tapped holes 
of the motor mount through the 1/8 
inch holes in the titanium plate. If the 
holes are not visible, drill the holes 
out with a larger sized bit. Or, use a 
Dremel tool with an end mill ball 
attachment to turn the holes into 
slots. Make sure the motor mount will 
fit before moving to the next step. 





BUILDER TIP: 

If the 
titanium 
proves too 
hard to 
penetrate 
with a 
hand drill, 
use a drill 
press. 



MM* 



ASSEMBLING THE DRIVETRAIN 

STEP 5: MOUNTING THE MOTOR MOUNTS 

Attach the two motor mounts to the motors. Slide the motor mount over the 
motor shaft, and place it on the front of the gear box. Rotate the motor mount until 
the two tapped holes are visible through the guide holes on the motor mount. Using 
the 256 screws and the .05 inch Allen wrench, screw in two of the screws through 
the guide holes into the tapped holes on the motor. After mounting both motors to 




44 SERVO 10.2012 



the motor mounts, you will notice 
the motor mounts have tapped holes 
on all sides. Pick one of the two long 
sides and line up the tapped holes 
with the 1/16 inch holes on the 
titanium plate. 

Using the 1/16 Allen wrench and 
two 440 screws, screw them through 
the guide holes on the titanium plate 
into the tapped holes on the motor 
mount. Repeat this process on the 
other side of the robot, so both motors are mounted to the titanium plate. 




STEP 6: MOUNTING 
THE WHEELS 

Take the FingerTech hubs and 
glue them to the lite flite tires. Start by 
running a line of glue down the 
length of the Fingertech hub, and 
slide a lite flite wheel over the shaft of 
the hub. Repeat this process on both 
wheels. 

Slide both assembled wheels over 
the drive shafts of your robot. Line the 
set screw of the hub to the flat on the 
drive shaft. Warning: If this step is 
skipped, your wheels will fall off! Use 
the .05 inch Allen wrench to tighten 
the set screw in the hub. 




SOLDERING THE ELECTRONICS TOGETHER 

STEP 7: STRIPPING THE WIRES 

We are going to start by stripping the wires on both FingerTech controllers. 
Also strip the red and black wires on the female JST plug. 




Tin all six leads. To tin each lead, get the soldering iron to full temperature. 
It usually takes about 10 minutes on most irons. 

Heat the wire with the iron while placing the solder on the other side of 
the wire. If the wires are not taking the solder, apply a little bit of solder to the 
iron. After tinning all six leads, we will now join the three black leads together. 




SERVO 10.2012 45 



Slip a piece of heat shrink over the two black speed controller leads. Solder 
the JST connector to one of the speed controller leads. I recommend putting the 
speed controller lead in a vice or pair of pliers, then holding the soldering iron in 
your dominant hand and the JST connector in the other hand. Place them together 
so they are horizontally touching. Heat both wires with the iron until the tinned 
leads melt together. 




Once all three wires are soldered together, slip the heat shrink over the solder 
joint; make sure to cover all exposed wire. Use a lighter or other small flame to 
compress the heat shrink around the solder joint; make sure the flame does not 
touch the heat shrink. After joining the black leads together, repeat the process 
and join the red wires together using the same steps you did on the three black 
wires. 




Now, let's solder the speed 
controllers to the motors. Tin the red 
and brown leads on both speed 
controllers, then tin both motor 
leads. When looking at the back of 
the motor, you will notice one lead 
has a red dot next to it. This 
indicates it is the positive lead. You 
will then solder the red wire to the 
positive lead on the motor. On the 
second motor lead — which is not 
marked — you will solder the brown 
wire. Repeat this process on both 
motors and speed controllers. Once 
you've soldered the last brown lead, 
you will have officially soldered 
together your first combat robot! 




46 SERVO 10.2012 



MOUNTING THE 
COMPONENTS 

Cut out pieces of double-stick 
tape, and stick one piece to the back 
of the receiver and a second piece to 
the back of the Li-Poly battery. Stick 
the receiver just below the right 
motor, and stick the battery just 
below the left. 

Now, cut two more small pieces 
of double-stick tape and attach them 
to the speed controllers down 
between the motors. Plug the long 
receiver leads coming off the speed 
controllers into the receiver in the 
aileron and elevator slots. 




BUILDER 
TIP: 

Put the 

double-stick 

tape on the 

label side of 

the speed 

controllers. 

Although 

this will cover the label, 

make the LED visible. 




CONNECTING THE RADIO TO THE RECEIVER 

Plug the "bind" plug into the receiver on the battery port. Then, power on 
the robot by plugging the 7.4 volt 
battery into the JST lead. The receiver 
should start, showing a blinking 
orange light. Now, on your radio, flip 
the mix channel to the upright 
position. Flip 

the elevator and mix switches to the 
upright position, as well. 

Hold the "train" switch and turn 
the radio on. You 
will wait to see the 
blinking light on 
the receiver and 
the transmitter go 
solid. This indicates 
the transmitter has 
"bound" to the 
receiver. 







MAKING THE BOTTOM PLATE 

When I originally designed the bottom plate for this wedge, I used a piece of 



cardboard (or "cardboard aided design") 
article link to trace onto polycarbonate. 
With polycarbonate this thin, you can 
cut it with hand shears and bend it in a 
vice. Carefully lay the pattern out and 
with either a pencil or fine-tip Sharpie, 
trace the pattern onto the 
polycarbonate. Then, using the hand 
shears, cut out the bottom plate. The 
dotted lines on the pattern represent 
where it will be bent in the vice. 



I have provided a cut-out for you at the 



it will 





SERVO 10.2012 47 



One special note: I don't drill the holes until after the material is bent. This 
goes against many shop practices, however, for garage and hand tools I believe 
this is a better approach. Start by bending the front of the plate to a 30 degree 
angle. With polycarbonate, you will need to bend it past the point and see where 
it returns. Move to the dotted line — 1 .5 inches from the top — and bend it to 30 
degrees. The tip of the plate and the middle of the plate should be lined up and 
pointed in the same direction. 




FINISHING 
YOUR ROBOT 

Once the bottom plate sits flat 
on the robot, use the fine-tip 
Sharpie and mark the locations of 
the tapped holes on the motor 
mount. Because the polycarbonate 
is clear, you can lay it on the robot 
and see where the tapped holes 
are. Once you have marked them 
with a pen, use the same punch, 
hammer, and drill technique 
described previously to drill out the 
marked holes. 



Flip the plate over and bend the back panel to 90 degrees. Bend the two 
small side tabs up to 90 degrees. Place the covering over the two motor 
mounts, and check the fit. You may need some additional tweaking to get the 
piece to sit flat against the two motor mounts and the front of the titanium 
sheet. 




r - m 




48 SERVO 10.2012 



Screw down the polycarbonate 
plate with four 440 screws. Then, 
place your robot face up on a block 
of wood; make sure you can see the 
wood through the three titanium 
holes on the front of the robot. Using 
your 1/8 inch drill, penetrate through 
the polycarbonate sheet and titanium 
plate. After drilling each hole, add 
440 screws to help hold the 
polycarbonate sheet in place. 




BUILDER 
TIP: 

You can 
make your 
wedge flush 
to the ground 
by filing the 
edge of it. 



"WHEELS ON THE GROUND" TEST 

If the robot's steering is incorrect, try flipping the aileron and elevator 
switches to different positions. There should be four different combinations. 
If none of the four combinations work, you will have to open the robot and 
flip the two speed controller plugs to opposite ports. However, your first 
power-on should be correct. 

You have now finished a one pound version of my 150 gram robot 
Wadgie. Wadgie has served me faithfully for five years now. He has endured 
more hits than any of my other robots. The design has worked well for me. I 
hope it will work well for you. 




READY FOR THE ROAR OF THE CROWD 

Learning how to construct an actual platform for a robot is an important 
first step. Once you have mastered the basics with your durable wedge bot, 
you can then put your imagination and your newly learned building techniques 
to work to construct a robot entirely of your own creation. A further benefit is 
you will have a basic wedge robot to practice against. I never started winning 
matches until I had two robots and 
practiced driving them at home. 

Please remember to be 
safe and follow good safety 
procedures. Wear safety glasses 
through the entire build process. 
Do not use power tools you're 
unfamiliar with. 

Stay tuned to SERVO Magazine 
for a future article where I will 
show you how to add a lifter or a 
clamp onto your robot. 

I wish you good building and I 

hope to 

see you in 

the ring. 

SV 





www.servomagazine.com/index php?/ 
magazine/article/ctober2Q12_Lytle 

Discuss this article in the SERVO Magazine forums at 
http://forum.servomagazine.com 



SERVO 10.2012 49 



FINNIC HEM 

Take the pain out of putting your robot's remote 
sensor to work by translating its RS-232 data stream 
into a TCP/IP packet. 



Gathering sensor data with a 
robotic device usually entails some 
sort of 802.15.4 network. If you 
want to forward the collected data 
to a remote site, then TCP/IP is 
required. The hardware and 
firmware to move those special 
little bits of sensor data can be very 
complicated to build and program. 
However, I've devised a way to take 
the pain out of putting a remote 
sensor to work. My method does 
not require one byte of user written 
TCP/IP code and you don't have to 
scratch-build any Ethernet devices. 

50 SERVO 10.2012 



by Fred Eady 



www.servomagazine. com/index, php?/ 
magazine/article/october2012_bady" 

Discuss this article in the SERVO Magazine 
forums at ttp://forum. servomaqazine.com 



The Big Picture 

Let's start at the sensor end. It 
really doesn't matter what you are 
sensing or what you are using for a 
sensor as long as it can provide 
analog or digital data that can be 
represented in binary. The sensor 
passes the binary data along to a 
resident microcontroller via the 
microcontroller's analog or digital 
inputs. Once the microcontroller 
massages the data and assembles it 
into a data package, the formatted 
data is passed to a short-range low 
power 802.15.4-based radio. 

Radios need each other. So, 
there's probably another 802.15.4 
radio within ear shot of the sensor 
radio. The data stops here unless you 
have equipment installed that will take 
those sensor bits on a ride to 
somewhere else. 

I'll leave the nature of the sensor 
to you. However, I'm going to put a 
PIC18F4620 between your sensor and 
a Microchip MRF24J40MA 802.15.4 
data radio. On the remote end, I'll 
place another PIC18F4620 behind yet 



another MRF24J40MA data radio. To 
keep the sensor-generated bits from 
piling up in the bit bucket, I'll attach 
the remote PIC18F4620 to a device 
server. 



Device 
Server?? 



That's what I said. A device 
server is an electronic module that 
accepts a non-IP-based protocol and 
formats the data represented by the 
protocol into an addressable IP-based 
protocol that can travel on a LAN, a 
WAN, or the Internet. In our design, 
the non-IP protocol will begin with a 
START bit followed by eight data bits 
and a STOP bit. If you added NO 
PARITY to the aforementioned data 
stream, you correctly identified our 
mystery protocol as RS-232. Thanks to 
the PIC front end, our device server 
can accept any serial protocol that can 
be represented in byte format. The 
device server of choice is offered by 
the SENA Corporation and is called 
the NEMO10. 

NEMO10 is billed as a single-chip 
network enabler module. A glance at 
Photo 1 seems to prove that out. 
Actually, NEMO10 is a multi-chip 
serial-to-Ethernet converter housed in 
a compact DIL configuration. 
NEMO10 is composed of an 8032 
microcontroller, 256 KB of static RAM, 
program Flash, 64 KB of EEPROM, and 
a NIC (Network Interface Controller). 
The NEMO10 is network-ready 
because it is shipped with a unique 
burned-in MAC address. The only 
networking hardware component 
missing is the Ethernet magnetics 
module. The NEMO10 is designed to 
interface with the XFMRS, Inc., 
XF10BASE-COMBO1-2S Ethernet 
magnetics/filter combo module which 
is under the lens in Photo 2. 

Like many of today's modern 
microcontrollers, the NEMOIO's UART 
is indigenous to the microcontroller's 
silicon. In addition to the Ethernet and 




PHOTO 1. The NEM010 is a compact serial-to-Ethernet converter module 
designed to interface any RS-232-based device to a LAN or the Internet. 



serial interfaces, the NEMO10 provides 
all of the necessary I/O drive for 
indicator LEDs. 

Using ARP, NEMO10 can resolve 
hardware (MAC) addresses using 
known IP addresses. The NEMOIO's 
ability to act as an ICMP client allows 
it to respond to a network ping. 
NEMO10 can request an IP address 
from a DHCP server and communicate 



via Telnet. NEMO10 can request an IP 
address, which infers that it may be 
able to perform other IP-based client 
and server functions using IP's best 
buddy, TCP. In fact, the NEMO10 can 
be configured as a TCP client, a TCP 
server, or a combination of both. 

If the NEMOIO's serial port is not 
available as a console port, a Telnet 
session can be used to manage it 



JXFMRS1227W] 
[XF10BASE- | 

j COMB0 1-23 ! 





PHOTO 2. You'll need this baby on the other side of the NEM010 which is 

designed to interface to Ethernet devices using this XFMRS, Inc., Ethernet 

magnetics module. There's also a pair of homemade headers in this shot. 

You'll find out why one is missing a pin later on. 

SERVO 10.2012 51 




PHOTO 3. The NEMO10-SK is 

a full-blown NEMO10 support 
system that includes RS-232 
and Ethernet interfaces. 



locally or remotely. There's also a 
PC application called HelloDevice 
Manager that can be used to manage 
the NEMO10. 

NEM0 10 Setup 



We can choose to configure the 
NEMO10 via its serial port or by using 
a Telnet session. At this point, our 
NEMO10 network consists only of 
what you see in Photo 1. To 



configure the NEMO10 by Telnet, 
we'll need to attach the XF10BASE 
Ethernet magnetics/filter combo 
module to it. If we decide to 
configure the NEMO10 using RS-232, 
we'll need an RS-232-to-TTL converter 
and a console/data toggle switch to 
allow us to force the NEMO10 to 
enter console mode. In either case, 
we'll also need to power the NEMO10 
with a power supply that can provide 
a minimum of +5 volts at 60 mA. 
I promised we wouldn't scratch- 




build any Ethernet hardware. The 
same goes for RS-232 hardware. So, 
instead of swinging a soldering iron, 
we'll support the NEMO10 with a 
test bed called the NEMO10-SK. The 
NEMO10-SK shown in Photo 3 
incorporates a male nine-pin RS-232 
connector that feeds an RS-232-to- 
TTL converter IC. An XF10BASE 
Ethernet magnetics/filter combo 
module is providing a 10 Mbps 
Ethernet interface at the opposite 
end of the NEMO10-SK. Power for the 
NEMO10 is produced by a switching 
power supply that is based on an 
LM2575. To take advantage of 
the NEMOIO's entire range of 
functionality, the NEMO10-SK also 
includes a reset switch, a factory reset 
switch, a data/console switch, a 
power switch, and a set of status 
LEDs. The NEMO10-SK test bed 
interfaces to the NEMO10 module 
with a set of 0.1 inch pitch female 
headers. The NEMO10 is shown 
attached to the test bed in 
Photo 4. 

If you don't have a network set 
up to support the NEMO10, using a 
serial connection is the easiest way 
to configure it. The NEMOIO's serial 
interface defaults to 9600 bps, eight 
data bits, no parity, and one stop 
bit. Screenshot 1 was produced by 
flipping the data/console switch to 
the console position and using 
HyperTerminal to serially log into the 



PHOT0 4.TheNEM010-SK's 
female headers supply power 
to the NEM010 and connect its 
module's internal electronics 
to the RS-232 and Ethernet 
interfaces. 



52 SERVO 10.2012 



NEMO10. I requested the 
NEMOIO's current IP and serial 
port settings using its get ip and 
get serial commands. As you can 
see, the NEMO10 comes up with 
DHCP mode enabled. Since there is 
no network, DHCP is useless and 
there is no IP address at this point. 

If we left the NEMO10 in 
DHCP mode, we may never be 
able to contact it remotely. 
Normally, DHCP IP address leases 
are set to expire and force the 
node to request a new and 
different IP address. We must 
always depend on the NEMO10 to 
be identified by one particular IP 
address. So, our first command will 
be to assure the NEMO10 can 
always be located via its IP 
address: 



1 


|__«L^_t_*__^ 


■ i» '1 - 




FJ, tdri Vir* Cpi TrjnrV Hrlp 




Dfi* 3 Q& tf 




login: adain 






password; *«-** 






Fyye "help" lo get Lonmdiid usag&s 






> get ip 






IP wode: dhcp 






fll lowed IP address: 6.0.8.0 






Allowed Subnet Hsk: Q.Q.Q.Q 






y y&t serial 






BouoVote: 9666 






Oata bits: & bits 






Parity; None 






Stop hits: 1 bit 






Flo*_cor>trolr Nocie 






DTR_option: fllffsy5„high 
OSR option: None 


SCREENSH0T1. The NEMOIO's 




In t er char_ t iheout C hs ) : 50 


serial console can be used to 




initially configure the serial and 






network parameters. 


- 




Here, I've logged in as admin 






using the default password admin. 




CnnnKtwHtfbtd A*n detect MAl frlw*l 







set ip static 192.168.1.97 
255.255.255.0 192.168.1.1 

With the NEMO10set/p 
command, we assigned a static IP 
address of 192.168.1.97 regulated by 
a subnet mask of 255.255.255.0. The 
network router's (gateway's) IP 
address is 192.168.1.1. Since we 
didn't specify and filter parameters, 
the IP address and subnet mask 
filtering remain disabled by default. 
We must use the NEMO10 save 
command to retain our 
configuration changes and the 
reboot command to bring them 
into effect. 

Now that we can operate on a 
DHCP-enabled network with a static 
IP address, just for grins let's throw 
the data/ console switch back to 
data mode and do the rest of the 
NEMO10 configuration with a 
Telnet session. 

Using HyperTerminal in 
Winsock mode, I logged into the 
NEMOIO's Telnet console port (23) 
using its newly assigned static IP 
address (192.168.1.97). As you can 
see in Screenshot 2, the NEMO10 
is now in static IP mode and all of 
the IP configuration data we 



entered is in place. 

I issued a get command to 
retrieve the NEMOIO's Admin, IP, 
Host, and Serial status you see in 
Screenshot 3. The IP configuration is 
just like we want it. However, we 
need to do a little bit of twiddling in 
the Host area. The Host_mode 
defaults to TCP Server (tcps); that's 
fine since we want to serve our sensor 



• r^MOEfr-Hftvd ■ 

Fl* fdri Vir* :«i Trjnilp. h»p 



data. I don't like the Localjjort 
assignment and the lnactivity_timeout 
is a bit much. So, let's use the set 
host command to alter the Host 
configuration: 

set host tcps 9000 10 

Our TCP server now times out 
in 10 seconds instead of 300 



login: adnin 
password; *«■** 

ly&e ' h&lp ' to get co*nai>d usages 
> gel ip 
IP_i»de; static 
IP_address: 132 168 1.97 
Subnet nqsk: 255.255.255.6 
Gateway: 192.163.1.1 
flll&ned IP.addresS: 9.6 9.6 
fl!icwed SijbnetjMsk: 0.0.0.0 



SCREENSHOT 2. The NEM010 is 

doing everything we told it to do. 

Now we are able to access its 

configuration console by way of 

a LAN or the Internet. 



Connected (HKH1 



■Mo detect TCP/IP 



M •"■pi 'ii 



SERVO 10.2012 53 



rtMOEE :=RVO ^,>-t.-.r»* 




SCREENSH0T3. 

Here's how the 

NEMOIOis 

configured at this 

point. There are 

still a few 

parameters we'll 

want to wiggle. 


D Or ■ . g O & Bff 




LlsemaNa: adnin 

Password: acfciin 

Oevicenawe: NEM01G Device 

— IP — 

TP_»de: static 

IP address: 132.168.1.97 

Subnet mask: 255. 255. 255. G 

Gateway: 1921631.1 

Allowed IP address: 9.9.9.6 
! Allowed Subnet rale: G 9.6 9 

Host 

1 Hosl node: Lcps 
I loc.al T port: 6691 

Inactivity tihetHJt(s&cl : 309 

Serial — 

1 fiaudrate: 9G0« 

Data_bits: B_bils 

Parily: Hone 

Stou_bits: l_bit 

Flop_controI: Hone 

ATR_oo t ion : ft I ways_bi gh 

OSFLoption: Mon& 

In t erchor_ t Liteou t ( ws ) : 59 

>- 




l[cnnnKt«JnUl:« Vtzh\ TLHIP 



seconds, and the TCP server's local 
listening port is 9000. 

The NEMO10 serial console is 
hard-coded to run at 9600-8-N-1. 
However, we can specify differing 
baud rates, bit lengths, parity, and 
stop bits that comply with the serial 
configuration of the device. With that, 
let's serve the remote PIC18F4620 
at 19200 bps, eight data bits, no 



parity, and one stop: 

set serial 19200 8 n 1 n h n 

50 

The set serial command we just 
issued sets our new device baud rate 
at 19200 bps with eight data bits, no 
parity, one stop bit, no flow control, 
DTR always high, DSR "don't care" 



NEMGin-ESRTO- 
fill Edit Vnw Cri Tnnrfv Hrfp 



attain 

* SERVO-SENSOR 



Useman&L 

Password: 

Oevi ceriane : 

— IP — 

IP Hde: static 

IP_addr&ss: 192 J68. 1.97 

Subnet _nask: 255.255.255.9 

Gateway: 192.1G&-1.1 

Allowed IP.address: 6.9.6.9 

Allowed Subnet. Hsk: 6.9.9.9 

- Host — 
Hos(_nude: leps 
Local ^port: 9699 
Inact l yi ty_ t ineou t ( sec ) : 5 

Serial 

eaudrate; 19299 
Data_bits: S_bits 
Parily: Hone 
Stoid&its: l_bit 
F 1 o»_con Irol : None 
0TR_option: Alwavs_high 
DSFLoption: Non& 
Intercbar_tiHeaLjt(ws) : 56 
> _ 



SCREENSH0T4. 
With all of the IP, 

Host, and Serial 

parameters 

configured to 

our taste, it's 

time to test our 

SERVO-SENSOR 

device server 

node. 



with an inter-character timeout of 
50 ms. While we're at it, let's 
identify the sensor node as SERVO- 
SENSOR: 



set admin 



SERVO-SENSOR 



tDnn*ciKi3*Ja ANSJW 



r 'lH IP 



The asterisks retain the 
previous values of the set admin 
command's Username and 
Password parameters. Only the 
Devicename parameter is changed 
as verified by Screenshot 4. Note 
also that the device serial port now 
has a baud rate of 19200 and the 
Devicename has changed. At this 
point, another save and reboot 
is in order. 

We have one more 
configuration task to complete. It's 
not a physical NEMO10 task, but it 
affects the NEMO10 directly. We've 
got to punch a hole in our gateway 
(router) to allow the outside world to 
access the NEMOIO's server 
functionality. All we have to do is tell 
the gateway to accept and allow 
passage of incoming TCP traffic 
addressed to 192.168.1.97 port 9000. 
I've done this in Screenshot 5. 

NEM010at 
Your Service 

We don't have an 802.15.4 
network running yet. However, that 
won't stop us from serving up 
some ASCII with SERVO-SERVER. 
I've always shown you data 
transfers with either HyperTerminal 
or Tera Term Pro. There's a really 
good terminal emulator/serial 
analyzer that comes with the CCS 
PIC C compiler. It's called the Serial 
Input/Output Monitor. I've set up a 
Winsock connection using the Serial 
Input/Output Monitor in 
Screenshot 6. 

The PIC18F4620 connected 
serially to the NEMO10 is part of a 
PICDEM Z development board. The 
PICDEM Z development board you 



54 SERVO 10.2012 



see attached to the NEMO10 in 
Photo 5 is one of a pair of 
802.15.4-capable development 
boards. The NEMO10-to-PICDEM Z 
direct serial port connection is 
possible because the NEMO10 is a 
DTE (Data Terminal Equipment) 
device. Your PC is configured as a 
DTE device. The PICDEM Z is wired 
for DCE (Data Communications 
Equipment) operation. Modems 
are DCE devices. A DTE device's 
transmit pin is positioned in the 
connector to directly connect to 
the DCE device's receive pin. The 
same holds true for the DTE's 
receive pin and DCE's transmit pin. 
Add a ground pin to this equation 
and you have what is termed the 
three-wire serial interface. 

Now that we have a device 
server to device serial connection, 
let's write a simple piece of code to 
spin something out of the PIDEM Z's 
serial port: 

unsigned int servo = 0; 
do{ 

Printf ("YOU HAVE CONTACTED 

SERVO- SERVER ") ; 

PrintDec ( servo++) ; 

Print f ("\r") ; 

DelayMs (1000) ; 
}while(l) ; 




*■ ■! I ■ 111 Mf 



- 




Dn-r-rilV 


— r.,»-i_, 
-'- ■■- 
"-^" <-t-m 


: 



□n 

□En 



SCREENSHOT 5. This particular 

router calls the NEM010 a virtual 

server. You should recognize the 

IP address and port numbers, 

considering we assigned them. 



OPTO ISOLATOR 



I NTERfl ALTO METER «■ 
INTERNAL TO METER «" 




N^ 

^ 



DTR 



fc BTS 



"E51T 



NtMOiOMALE 



SCHEMATIC 1. This is very clever and cheap. 

This circuit eliminates the need for a more costly 

RS-232-to-TTL converter. 



The Printf statements are not 
your normal printf statements. The 
Printf and PrintDec are user written 
routines that do not accept any of 
the normal printf formatting. 
Basically, the code snippet runs 
forever, sending the incrementing 
servo variable message to the 
NEMOIO's serial port. 

Everything is now in place and 
we can perform a preliminary test. 
Clicking on the Serial Input/Output 
Monitor CONNECT button should 
establish a TCP session with the 
NEMO10. If our little test program is 
running, we should see the message 
from the PIC18F4620. I've started 
the PIC and I can see that the 
NEMOIO's serial RX LED is blinking. 



PHOTO 5. The PICDEM Z 

development board is very useful 

when you have to lash together 

a simple 802.15.4 network. The 

serial port plug-to-plug works 

because the NEM010is 

configured as a DTE and the 

PICDEM Z is wired as DCE. 




SERVO 10.2012 55 








SCREENSH0T6. The 

Serial Input/Output 
Monitor can do 
everything that 
HyperTerminal can do 
and more. The serial 
Input/Output Monitor is 
partoftheCCSPICC 
compiler package. 



• era* 



I Uliii.uiiiii.il 



I also have an illuminated Ethernet link 
LED and a glowing System Ready LED. 
After establishing the connection — in 
addition to the LEDs I just listed — I 
see a blinking Ethernet Activity LED 
and Screenshot 7. 

The TCP connection will stay up 
as long as the PIC18F4620 is sending 



data. Recall that we set the inactivity 
timeout for five seconds. If the PIC 
stops sending on its serial port for 
more than five seconds, the TCP 
session will be terminated by the 
NEMO10. To test this, I stopped the 
PIC and five seconds later the Serial 
In/Output Monitor DISCONNECT 



4 "j*ti illii5M-.Ci.qi.ru an (a 





OU HAVE CONTACTED SERVO-SERVER 5D 



SCREENSHOT 7. This is the PIC18F4620 talking to the NEMOIO's 

serial port at 19200 bps. Note the hexadecimal translation and 

status LEDs at the bottom of the shot. 



S*F » * *l ft ij » » * < 9i -H 1J M * ** £ 5* « F? w * \n 5) 45 Si « -* 5,- W H U *■ 
I» r 11 B 4 41 ^ B XI '] f f H 1L U 14 C « 3f U fl)ZH4f31]DlZH«Sa!»]4D 
» -T II M M -I !* 41 p +3 -T ■* 14 -4L 41 h -»a ■**■ & U 4E S3 M -W J) EJ 4S si U -fl \? Jt H is x. 

DSA * 0« * tfS # Aha « trwr * ftrart * TM * RHO # RT* « 



1K1J5U9 



Knrn met 



button returned to the CONNECT 
state, and all of the status LEDs 
indicated a dormant interface. I 
then clicked on the Serial 
Input/Output Monitor CONNECT 
button without restarting the 
PIC18F4620. Sure enough, five 
seconds later the NEMO10 
dropped the session. 

Serve a Meter 



I just happen to have a Tenma 
72-7750 modern digital multimeter 
on the bench. This little orange 
drop can do capacitance, 
frequency, and temperature 
measurements, as well as the 
standard voltage and amperage 
measurements. However, before 
we can tap into its features using 
the NEMO10, there's a little bit of 
work we have to do. 

The first task is to understand the 
Tenma's serial interface which isn't 
really a regulation RS-232 serial 
interface at all. I've outlined the 
Tenma's "RS-232" interface in 
Schematic 1. The opto-isolator 
consists of a light transmitting 
element (IR LED) internal to the 
meter and a light receiving module 
(IR transistor) terminated with a 
female DB9 connector that plugs 
into the meter. The circuit works 
by allowing the NEMOIO's DTR 
line to drive the collector of the 
opto-isolator's transistor logically 
high (1). The NEMOIO's RTS line 
provides a virtual ground return 
which is really a logical low (0) 
perpetuated by driving the RTS line 
to a logically low level. When the 
modulated IR light source is 
illuminated, the opto-isolator's 
transistor conducts and a logical 
high is presented to the NEMOIO's 
RXD pin. 

Conversely, when the IR LED is 
extinguished, a logical low is 
presented to the NEMOIO's RXD 
pin. The resistor between the opto- 
isolator's emitter and virtual 



56 SERVO 10.2012 



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ground makes the logic shifts 
possible. 

Recall that we can configure 
the NEMOIO's DTR line to remain 
logically high at all times. The 
problem is that we can't 
programmatically control the 
NEMOIO's RTS line. Being a DTE 
device, the NEMO10 will drive the 
RTS line logically high by default. 
So, to get the right logic level at its 
RTS pin, we simply isolate the 
electrical connection between the 
NEMO10 and the RS-232 converter 
input. 

Removing the electrical 
connection forces the RTS input pin 
to float. The pin really isn't floating 
since there is an internal pull-up 
resistor on the RTS input. Since the 
translator gates are all inverters, a 
logical high on the RS-232-to-TTL 
converter's RTS input pin produces 
a logical low at its output pin. I performed the isolation 
by building up a couple of 12-pin male-to-female headers, 
plugging the NEMO10 into the new set of headers, and 
clipping off the new header RTS pin. 

The use of RS-232 logic levels allows the circuit 
depicted in Schematic 1 to replace a more expensive 
RS-232 converter IC. By the way, the Tenma runs at 
19200-7-O-None-1 (19200 bps, seven data bits, odd parity, 
no flow control, one stop bit). According to Screenshot 8, 
it's 23° Celsius in the shop. 

RS-232 is Far From Dead 

The only soldering we performed was to assemble the 
12-pin headers. The only code we wrote was for test 
purposes and didn't include any TCP/IP stack elements. 
Using the NEMO10, we managed to serve up some ASCII 
data from a PIC18F4620 and some temperature data from 
an off-the-shelf multimeter. Now that you know what a 
serial device server is and how to use it, apply what you 
have learned to that robotic device you're building. 






Ntvttyw; hu) Rfc 




SCREENSHOT 8. Ignore the 4800 as 

the meter is designed to interface 

with a factory-supplied GUI. It's 23° 

Celsius in the shop. 



j 



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Sources 



Lemos International 
Co v Inc* 

NEMO10 
wwwJemosintxom 



Custom Computer Services 

Serial Input/Output Monitor 
CCS PIC C Compiler 
wwwxcsinfoxom 

Microchip 

PICDEM Z 

www*microchip*com 



RF Specialists 



From Pari \5ta Pari 9Q£un\p\;n 
NprowftifMrFAr.WFN4ir;i'CFiff 



RF Modules Data Loggers 

Frgm Pari \ J r Pari 90 Cnrnpfinn t 5(fl*rf Afone flfttf 

Industrial Bluetootti ZujBeePro 

flFM- AtaluK W\Tfk%f Der-tr fervor* HS-J! J 2 GEM MMti tf.nrf USA 2r$fr« Sittki, 




RrecisionlQuartz Oscillators 



Excellent rnase n disc pcrionnance 



RF Design services 

■stpund to wprft nr-irh yvur nrfainr mpinwrjir 

"'-nto\mp\emtTfWtorr, 



B66.245.3Ci£" 



X4 LEMOS 

INTERNATIONAL 



V r INTERNATIONAL tal*s05l&mo*1nt r c*r 

'Mu kintf yaur RF idea & In t v p ruji tuhi c j p r t.nl u c t 



SERVO 10.2012 57 



TROUBLESHOOTING 

TIPS and 

TRICKS 




HOW TO KEEP THINGS 

FROM GOING WORNG 

WRONG WITH YOUR 

ARDUINO-BA5ED BOT 

by Gordon McComb 

www.servomagazine.com/index.php7/magazine/article/october2012_McComb 

Discuss this article in the SERVO Magazine forums at ttp://forum.servomagazine.conri 



"Where nothing can 
possibly go wrong!" 
That was the catch phrase 
to the 1973 movie, 
Westworld. You remember 
what happens ... some 
programming glitch causes 
all the human-like robots 
in the Westworld theme 
park to go haywire. 
A particularly nasty 
gunslinger bot goes after 
the two heroes of the 
movie, shooting one dead 
(Josh Brolin's dad no less!) 
and then chasing after the 
other until its face gets 
burned off with acid. 

58 SERVO 10.2012 



I never give my robots six-shooters 
for this very reason. I know 
sooner or later something won't 
work the way it should. It's bad 
enough to have to troubleshoot 
problems with batteries, let alone 
worry if my robot will shoot me in the 
back one dark night. 

Troubleshooting is the step-by-step 
process of determining the root cause 
of a particular problem, whether it's 
electronic or mechanical. It's one of 
the core arts and sciences of robot 
building. In this article, I'll provide 
some basic advice on how to 
troubleshoot your Arduino-based bots 
— gun fighter or otherwise. 

Systematic 

Approach 

to Development 

and Troubleshooting 

Simple bots only need simple 
troubleshooting. They only have one 
or two features, and when 



something's wrong, the reason is 
usually obvious. Add complexity to the 
design — even something as 
innocuous as a separate set of 
batteries for the servo motors — and 
you're left wondering where to start 
in troubleshooting any problems. 
Layer upon layer of features and 
functionality create ever-increasing 
combinations of trouble hot spots. 

As a system gets larger, working 
out the kinks becomes much more 
difficult. One of the best ways to test 
these kinds of systems is to break 
them down into smaller and more 
manageable units. 

• Avoid the shock of a non- 
functional robot by building it in 
smaller pieces. Begin with the basic 
drivetrain — connect just the motors 
and battery to the Arduino (through a 
suitable H-bridge or other suitable 
circuit, as needed). 

• If this part works, you're ready 
to move on by building and testing 
each new capability separately. Add 



Start With a Preflight Check 




FIGURE! The first order 

of business is to always 

verify that the Arduino's 

battery connection is 

solid. Both ends of the 

cable are potential weak 

points, where wires can 

break off and cause 

interruptions in the 

power supply. 



Ever heard the phrase "kicking the tires?" In the early days of the automobile, tires were made of a much 
thinner rubber than they are now. "Kicking" them before setting off on a trip would help a motorist know if 
the tires were ready for the road. Better to catch problems early. You can "kick the tires" of your Arduino 
robot by going through a kind of preflight check list that demonstrates 
all systems are ready. 

Start with a visual inspection of the Arduino itself, its 
battery or other power connection (like the type in Figure 1), 
and all wiring. Note if anything's become disconnected or 
loose. If you're programming the Arduino or powering it from 
your PC's USB port, be sure the cable is snugly inserted on both 
ends. USB cables and their jacks can become damaged during 
normal use — wires kink and plug contacts get bent or broken off. 

If you suspect a problem has developed but aren't sure of the cause or 
how extensive it is, then upload a "signs-of-life" sketch to the Arduino to test 
basic operation. A good signs-of-life demonstration is the LED blink example 
sketch, or load up something like the one in Listing 1. 

Upload it to the Arduino, then watch for the tell-tale flashing of the LED 
on pin 13 of the Arduino. (Naturally, you can't use this method if your 
Arduino has something plugged into pin 13 that otherwise might alter the 
behavior of the LED. An example is a switch input where you've added your 
own pull-up or pull-down resistor. These external components will override 
the operation of the Arduino's built-in LED, causing it to either stay on all the 
time or not flash at all.) 

If you have a shield plugged into your Arduino, you may wish to 
temporarily disconnect it before running any signs-of-life sketches. Removing 
the shield disconnects any electrical components that might be interfering 
with the operation of the Arduino. Parts on a shield can go bad or short out, 
and those faults can prevent the Arduino from powering up or working 
correctly. 



Listing 1 — Blinker.ino 



boolean ledState 



false; 



void setup () 

pinMode ( 13 , 
} 



OUTPUT) 



void loop ( ) { 

digitalWrite(13, ledState) , 
ledState = ! ledState; 
delay(500) ; 

} 



just one feature or capability at a 
time. Avoid the temptation to 
implement ultrasonic range finding, 
infrared detection, and music playing 
all at the same time. Each of these is 
a discrete unit; test each one to 
determine if that function is working 
properly. 

• After building and testing the 
core blocks of your robot, 
methodically integrate them with the 
rest of your system. Start with those 
that are critical to the design of your 
robot, plus have the most impact on 
the operation of the Arduino. This 
allows you to more readily isolate 
problem areas up front. For example, 
music and sound playing can consume 
considerable processing time. 
Integrate it early with your 
robot's basic motor function. 
Add the other features (one 
at a time), like the ultrasonic 
and infrared sensors. By 
introducing the most 
demanding functions first, 



you can readily determine which 
additional function "breaks the 
camel's back," so to speak. You can 
then decide if another programming 
approach is preferred, or which 
features to keep. 

The same systematic techniques 
may be used to troubleshoot a 
fractious bot. Test each subsystem 
separately; ideally, electrically isolated 
from the rest of the components. That 
may mean partially disassembling your 
robot and disconnecting parts you 
don't need. Circuitry on the music 
playing shield may be interfering with 
some other piece on your robot; 
remove the shield completely, don't 
just rely on commenting out the music 



Tip! Apart from easily resolvable problems like loose 
wiring or worn out batteries, the interaction of the 
specific combination of circuitry on your robot is the 
main cause behind technical glitches. Some hardware 
may not be widely compatible with others, for example 



playing code. Similarly, sensors and 
other components individually 
plugged into your robot's Arduino 
should all be removed, then replaced 
one at a time for testing. 

Or, circuits like cellular phone 
boards may consume copious 
amounts of current which can cause 
constant or intermittent errors. In the 
case of a cell phone SMS shield, for 
example, the circuit may draw an amp 
or two when transmitting. If your 
robot's power supply can't handle the 
peak load, the sudden draw can cause 
the Arduino to momentarily shut 
down. 

These so-called brownout events 
can be hard to track down, because 
the problem may only rear its 
ugly head when other current- 
consuming circuits are added 
to the mix. Remove any single 
circuit, and your bot functions 
again. Add it back in, and the 
problem returns. On the 
surface, this kind of mayhem 

SERVO 10.2012 59 



can look like a fault in the individual 
circuits when it's really just a matter 
of overtaxing the battery. In cases like 
these, using a bigger battery or 
completely eliminating circuits that 
draw excessive currents usually solves 
this problem. 

Using the 
Serial Monitor to 
Debug Problems 

Get into the habit of validating 
the operation of your robot and its 
Arduino processor by using the Serial 
Monitor window. This tool allows you 
to send messages from the Arduino 
back to your PC. These messages 
serve as a way to quickly and 
efficiently debug many aspects of 
your robot/Arduino — all at the same 
time. While you must take a few 
moments to set the debugging 
environment, it can save considerable 
time in the long run. 

No doubt you've already used the 



boolean ledState = false; 


1 


Listing 2 — Debugger.ino 


void setup () { 






Serial. begin (9600); //Match in 


Serial Monitor 


delay(250) ; 






Serial .print In ( "Setup complete ! " 
} 


; 




void loop ( ) { 






digitalWrite(13, ledState) ; 


// 


LED on or off 


Serial .print ( "LED on: "); 


// 


LED state in 




// 


Serial Monitor 


Serial .println ( ledState) ; 


// 


Shows or 1 


ledState = ! ledState; 


// 


Toggle LED state 


delay (500) ; 
} 


// 


Wait 1/2 second 



Serial Monitor to display messages 
from the Arduino, so you already 
know the basic concepts. Just in case 
the idea is new to you, here's what's 
involved: 

1. The hardware serial port is 
configured in the setup() function. 
Merely add: 

Serial. begin(9600) ; 

some place within setupQ, preferably 



near the beginning. The 9600 value is 
the baud rate — the data rate that the 
Arduino and PC will communicate 
with one another. This value is actually 
rather low, and both your computer 
and Arduino are capable of talking to 
one another at much faster speeds. 
However, 9600 baud is the most 
common rate used in the various 
Arduino examples. 

2. Debug messages are sent from 
the Arduino to the PC by using one or 



Good places to insert a Serial. print 
statement include: 



Inside the setup() function to verify that the 
Arduino is progressing to at least that point in its 
program. The Serial. print statement must appear 
after Serial. begin. If printing text immediately after 
Serial. begin, consider adding a quarter to half 
second delay: 

Serial. begin(9600) ; 

delay (500); // Wait half a second 

Serial .println ( "Setup ! " ) ; 

Inserting a debug statement inside setup() also helps 
you to verify that the Arduino runs the setup code just 
once. If you see the "Setup!" message repeat, it could 
mean your Arduino is being reset over and over again. 
This can occur, for instance, if the Arduino is not getting 
enough voltage to operate reliably. 

At the start and/or end of the loop() function to 

check that the Arduino is properly completing each loop. 
You can use static text, as in: 

Serial .println ( "Looping ! " ) ; 

or set up a more elaborate system where you indicate the 
number of loops that have elapsed so far: 



int counter 



0; 



void setup ( ) { 

Serial. begin(9600) ; 
} 

void loop ( ) { 

Serial. print ("Loop: w ); 

Serial .println (counter++ ) ; 

// rest of code 
} 

Be careful when using debug statements in the 
loop() to prevent over-running the communications 
between the Arduino and your PC. If the loop doesn't 
contain programming statements that require at least 
half a second to execute, (temporarily) slow things by 
inserting a delay at the bottom of the loop: 



delay (500) ; 



// Wait half a second 
// before proceeding 



Inside a user-defined function to verify that the 
function is being called. User-defined (your own) 
functions are a handy way to execute the same code 
whenever a certain event occurs. A good example is 
making the robot stop, back up, turn, and head off in a 
new direction whenever one of its touch sensor switches 
is activated. You can verify that the Arduino is reaching 
the user-defined function simply by adding a debugging 
statement as the first program line within it: 



60 SERVO 10.2012 



more Serial. print statements, like this: 

Serial .print ( "ok" ) ; 

which sends a simple "ok" to the PC. 
This statement sends just the text and 
no new line character. So, when you 
view the debugging information in the 
Serial Monitor window, all the text will 
appear on the same line. If you'd like 
it to show up on different lines, use 
the variation: 

Serial . println ( "ok" ) ; 

3. To actually see the debugging 
messages on your PC, you need to 
open the Serial Monitor window 
which is a feature that's built into the 
Arduino IDE software. After a sketch 
download is complete, just click on 
the Serial Monitor icon and the Serial 
Monitor window will appear. Verify 
that the baud rate setting in the lower 
corner of the window is the same as 
the Serial. begin statement used in 
your sketch. Otherwise, the Arduino 



Arduino Serial Monitor Control Characters 

The Arduino's Serial Monitor supports a couple of control characters — also 
called escape sequences — that can come in handy when you want to display several 
debugging values at once. All control characters begin with a \ (backslash). Probably 
the most useful control character is \t which inserts a tab in the print statement line: 

Serial. print( M Some text here"); 

Serial. print("\t"); 

Serial. println( M Some more text"); 

You don't need to emplace the \t control character in its own Serial. print 
statement when using just literal strings like that shown above. You will need to if 
you want to mix literal strings plus numeric values from variables: 

Serial. print( M Sensors reading\t n ); // Explanatory text plus tab 
Serial. println(mySensor, DEC); // Value from mySensor variable 



or 



Serial. printfSensor 1 is: "); 
Serial. print(Sensor1, DEC); 
Serial. print("\t n ); 
Serial. printfSensor 2 is: "); 
Serial. println(Sensor2, DEC); 



// Explanatory text 

// Value in sensorl variable 

//Tab 

// Repeat for sensor 2 



and PC will not sync up with one 
another, and the Serial Monitor 
window will display either nothing or 
gibberish characters. Use Serial 



Monitor debugging whenever you 
want to verify a part of your code is 
working as it should. Listing 2 
provides a short working example. 



void rightBumperButton ( ) { 

Serial .println ( "Right bumper 
activated! " ) ; 
// rest of code 

} 

At parts of the sketch that use loops where you 
want to be sure that program execution eventually 
continues beyond the loop. Suppose your robot stops 
and waits for a bumper switch to activate. The code is 
part of a loop, like so: 



sketch simply by sending that value to the Serial Monitor 
window. For instance: 

int ping = getPing(); 
Serial .print ( "Distance is: "); 
Serial .println (ping, DEC); 
// rest of code. 

int getPing ( ) { 

// Code to read ultrasonic sensor 
} 



while (digitalRead(lO) = = 0) {} 

which means check the value of digital pin 10, and keep 
looping as long as the pin is low (0). All fine and good, 
but sometimes programming errors, wiring mistakes, and 
other gremlins can cause your program 
to simply stop at this loop and never continue. You 
can check that the loop eventually exits just by placing 
a debugging statement immediately after: 

while (digitalRead(lO) ==0) {} 
Serial .println ( "While loop ended \" ) ; 

Whenever you need to preview a value such as 
the result of a sensor. Imagine you have an ultrasonic 
range finding sensor, but aren't sure if you're 
experiencing problems because the value from the sensor 
isn't what you're expecting it to be. You can visually 
check any numeric or boolean value from within the 



In this abbreviated example, the code that does the 
actual reading from the ultrasonic sensor is contained 
in a user-defined function named getPing. You call that 
function with the line 

int ping = getPing(); 

The numeric value that represents the reading from 
the sensor is contained in the ping variable which you can 
use in a debugging statement. Note the DEC qualifier — 
it ensures that the number held in the ping variable is 
expressed as a decimal value. 

The Arduino supports other qualifiers, as well — such 
as HEX and BIN — which display the value as a 
hexadecimal (base 16) or binary number, respectively. 
Check the Arduino reference at the arduino.cc website 
for additional options. By far, you'll use the DEC qualifier 
the most. 



SERVO 10.2012 61 



Here are some of the most 
common problems that 
beset Arduino-powered bots, 
and the most common ways 
to fix things. 

No Power, No Lights — It's As Primitive 
As Can Be 

A completely non-functional robot strongly suggests a 
problem with the power supply. If you're having these kinds 
of problems, start first with your robot's brain — the 
Arduino. If the Arduino's power light is not on, the most 
likely reason is that it's not getting power. Start with these 
checks: 

• Weak or dead batteries. Recharge or replace. 

• Possible bad USB connection if powered from your 
PC. Check the connection to see if the cable is merely 
loose. Try a different cable if one is available. 

• Faulty power switch or wiring. Small switches can go 
bad, especially if struck hard during a collision. 
Inspect and replace as needed. While looking, see if 
the wires from the battery have come loose. Check 
the power connection (barrel plug) as it goes to the 
Arduino. 

Erratic Behavior 

Your robot is working, it just doesn't work all the time, 
or it occasionally behaves in bizarre ways. The most 
common reasons are: 

• The battery charge is running low. Replace, recharge, 
or increase the battery capacity (larger battery 
and/or higher voltage, as needed). 

• Bad wiring connection. A broken or loose wire 
anywhere — especially ground related — can cause all 
manner of problems. If using solid conductor wire, 
check with your meter while gently moving the wire 
side to side. You'll get intermittent continuity if the 
wire is broken inside the insulation. 

• Wet or dirty contacts. Water and dirt can cause 
intermittent connections. Wipe clean, dry, and try 
again. 

Lights On, No Serial Debug Messages 

Suppose the Arduino's power LED is glowing, but 
nothing seems to happen. What's more, you've used 
debugging messages in your sketch, and these messages 
are not appearing when you open the Serial Monitor 
window. 

• The USB cable is bad, or the wrong serial port is 
selected. This error can occur if you've previously 
uploaded your sketch and have reconnected the 
Arduino to your computer. Verify the integrity of the 
cable (see Figure 2; check the ends themselves) and 
make sure the proper serial port is selected. (If you 
have more than one Arduino, each one may be 
associated with a different serial port. Be sure you've 
picked the right one.) 

62 SERVO 10.2012 



FIGURE 2. USB cable ends 
can get dirty and crushed 
during the normal course 
of events. Visually inspect 
the Arduino's programming 
cable, and replace as 
needed. 




• Wrong baud rate selected in the Serial Monitor 
window. Be sure it matches the baud rate specified 
in your sketch. 

• Serial communications out of sync. Sometimes your 
Arduino and PC fall out of sync, and they will not re- 
sync unless you: A) reset the Arduino, and/or B) reset 
the Arduino IDE (close, then reopen it). 

Serial Window Displays Garbage 

When you open the Serial Monitor window to look at 
the debugging messages sent from the Arduino, you get 
garbage text instead. 

• Wrong baud rate selected in the Serial Monitor 
window. Be sure it matches the baud rate specified 
in your sketch. 

• The USB cable is bad. Verify the integrity of the 
cable, or try a different one. 

Debugging Messages Repeat When 
They're Not Supposed To 

You've added a debugging message to the setup() 
function of your sketch. It should display once in the Serial 
Monitor window, but instead it keeps repeating. 

• Arduino is resetting by itself. Look for causes of 
power brownout — the voltage to the Arduino is 
falling below the minimum required. When this 
occurs, the sketch spontaneously restarts. 

• Arduino is resetting via the serial port. On most 
versions of the Arduino, plugging or unplugging the 
USB cable causes the serial port to reset which, in 
turn, causes the sketch to reload from the beginning. 
Look for causes of spontaneous reset of the serial 
port which can occur, for example, if the cable or 
plug connection is bad, or if the Arduino is drawing 
too much current from your PC's USB port. 

Data Results Are Wrong/Unexpected 

You're getting debugging messages, plus the data 
shown is wrong or unexpected. 

• The sensor or other device is misconfigured. If you're 
checking the results of a sensor, make sure it's 



FIGURE 3. Loose or missing wiring - especially the 

common ground connections where separate 

electronics and motor power supplies are joined — 

can create intermittent errors in the operation of 

your bot Be sure all wires are firmly connected and 

properly seated, especially when using a solderless 

breadboard as shown here. 



properly configured and 
programmed. For example, 
an ultrasonic range finder 
sensor may be programmed 
to return distance in inches 
or centimeters (or raw 
microsecond delay of the 
echoes). The data will 
appear wrong if you're 
expecting it in a different 
format. 

• Sensor or other data in the 
wrong format. The 
Serial. print statement can 
use an optional data 

formatting argument, specifying if the data is to be 
shown in DECimal, BINary, HEXadecimal, or some 
other format. Be sure to use the proper formatting 
argument based on the type of data value. 

• Programming error. Though we try to avoid bugs in 
code, sometimes they creep in and muddle the 
results. This is what debugging is for — catching 
those mistakes so they can be fixed. Carefully analyze 
your programming code, and look for math mistakes, 
incorrect assumptions, and other errors that can 
cause the invalid data. For example, did you really 
mean to add those two numbers together or multiply 
them? 

Sketch (Program) Won't Compile 

The most annoying glitch when using the Arduino is 
some type of error that prevents the sketch from compiling 
and uploading. Though there are many reasons this can 
occur — including an improperly installed IDE software 
package — following are some of the most common 
reasons. 

• Syntax error in code. Check for proper spelling and 
capitalization of all Arduino keywords ... remember, 
it's digitalWrite, not DigitalWrite, digitalwrite, 
digitalRight, or some other variation. Also check for 
missing semi-colons, parentheses, braces, and other 
typical errors. 

• Incompatible version of IDE software. The Arduino 
IDE software has gone through many changes over 
the years, where some changes have "broken" 
existing sketch code. Be sure you're using the correct 
IDE version for your sketch. Unless there is a specific 
reason otherwise, it's best to keep your Arduino IDE 
up to date with the latest stable release. However, 




you may keep previous iterations installed on your 
computer, should you need to compile your sketch 
with an earlier version. 

• Missing or incorrect library. Sketches that must be 
compiled with one or more libraries require those 
libraries in specific locations — either the main 
libraries folder in the Arduino IDE program directory, 
or the libraries folder within your sketchbook 
directory. If installing a new library, be sure to exit 
and restart the IDE before attempting to use it. 

Everything Works Except The Motors 

Your Arduino appears to be functioning normally, but 
your robot's motors aren't turning. 

• Not enough current to power the motors. Motors 
can draw a lot of current from your robot's batteries. 
If the batteries don't deliver enough current, the 
motors may not turn or they may only turn slowly. 
Beef up the batteries to ensure proper motor current 
levels. 

• Separate motor power disconnected, discharged. If 
your robot uses a separate power source for the 
Arduino and its motors, the motor power may have 
become disconnected or the motor batteries may be 
discharged. 

• Shared ground disconnected. Robots that use 
separate battery supplies for the motors need to have 
the ground of the two power sources connected. 
(There are exceptions to this, such as when the 
control board for the motor is interfaced to the 
Arduino using an opto-isolator.) Otherwise, the robot 
may not operate reliably, or at all. So double-check 
the common ground connection (refer to Figure 3) 
between the two power sources. 

SERVO 10.2012 63 




The American Society of Agricultural & Biological Engineers (ASABE) is an educational and scientific organization that 
promotes the advancement of engineering and science. Among many other activities, ASABE sponsors an annual 
robotics competition for graduate and undergraduate university students. 

The ASABE Student Robotics Competition presents students with a different agriculturally-themed contest each year. 
For the 2012 contest, teams of students designed and built autonomous robots that were required to navigate a scale 
model of a cattle feedlot. The robots had to move along rows of cattle pens divided by fences. Each pen had a feed 
container. Feed was represented by a cargo of 6 mm Airsoft pellets which was carried by the robots. At the start of each 
run, a judge provided the contestant with an SD card containing the required weight of feed to be dropped into each pen's 
feed container by the robot. Each run was timed. 

When a run was completed, the feed containers from each pen 
were weighed. Teams were awarded points based on objective 
measures such as the speed and accuracy of their robot, and for 
subjective qualities such as the elegance of design. Teams lost points 

when their robot struck fences surrounding 
the pens, required human assistance to 
complete a run, or dropped feed outside of 
a feed container. At first glance, this contest 
looks similar to a lot of other student robot 
contests but the addition of the feed pellets 
added some interesting and fun dynamics. 
When a robot missed the feed container 
and dumped a load of pellets onto the 
ground, it didn't just lose points; it created 
an obstacle for itself as it had to navigate 
through the rolling, bouncing flood of 
pellets to get to the next pen. 
The contest is held every year at the ASABE International Meeting. 
If you get a chance, it's definitely worth checking out. 

You can read more about the ASABE Student Robotics Competition at 
http://abe-research.illinois.edu/ASABERobotics 

You can find out more about the ASABE organization at 
www.asabe.org 

64 SERVO 10.2012 





Judge weighing „. - -£ ,|— 

contestant's feed bags. 



SERVO 10.2012 65 



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68 SERVO 10.2012 



Parallax Eleu-8 



Quadcopter 



Part 2: 



The Electronics Setup 




www.servomagazine.com/index.php7/magazine/article/october2012_Bergeron 

Discuss this article in the SERVO Magazine forums at http://forum.servomagazine.com 

This is Part 2 of a review on the Elev-8 Quadcopter robotics platform from 
Parallax. Whereas Part 1 focused on the physical build, this part walks you through 
the testing and setup, including integration with an R/C transmitter and receiver, 
selection and care of Li-Po batteries, and the never-ending task of maintenance. 

SERVO 10.2012 69 




Introduction 

If you've successfully completed the tasks 
outlined in Part 1 you've built and prepared the 
basic platform, meaning you've balanced the 
props, tested and programmed the ESCs, 
checked the direction of motor rotation, installed 
the power harness, and verified that every nut 
and bolt is in its proper place. Now it's time to 
hook up and verify the operation of the onboard 
computer and the R/C receiver. 

HoverFly Open Board Setup 

The HoverFly Open Board onboard computer is what 
allows you to manipulate the motors with your R/C 
transmitter. For example, if you move the left lever of your 
R/C transmitter forward to increase throttle, the 
transmitter sends a signal to the Open Board which sends 
control signals to each ESC to increase the speed of 
rotation of each motor. You could simply assign one 
channel to each motor and — given enough practice — 
increase or decrease the speed of each motor 
simultaneously as needed. 

However, there's more to the onboard computer than 
allowing you to control four motors with a single control 
stick. Separate manual control of each motor is virtually 
impossible when it comes to pitch (tilting and moving to 
the left or right), roll (tilting and moving front or back), 
and yaw (rotating clockwise or counterclockwise) — 




especially when executed simultaneously in a modest 
wind. While it might be possible for someone to manually 
control all four motors while the craft performs a figure 
"8" in variable wind, it would probably take years of 
practice. They'd have no time to experiment with the 
robotics-specific aspects of the platform. 

The Open Board takes over the details of differential 
motor speeds, enabling you to control the craft with a set 
of joysticks built into the transmitter — even in a modest 
breeze. It accomplishes the feat with the help of a three- 
axis gyroscope. Moreover, if you purchase the optional 
ultrasonic range finder (within the operational range of 
the craft), you can set and forget the hover height. 

Photo 1 shows the HoverFly Board atop the Elev-8, 
wired for testing. The front of the board (which faces up 
in the photo) holds the ESC motor connector. On the left 
of the board are the connections to the receiver; in my 
case, the receiver that accompanies the Spektrum Dx6i 
transmitter. The USB connector, prop chip, buzzer, and 
LED status light are also visible in the photo. In this 
example, the purple light signifies there's a problem — I 
haven't finished connecting the ESCs to the board. 

Setup involves first downloading the latest firmware 
from the HoverFly site. You'll need a PC running Windows 
to operate the program. Then, run the HoverFly utility to 
verify that your transmitter and receiver are properly 
configured. In all, software setup and verification is a 20 
minute painless operation. The most difficult part is 
determining where to plug in which cable. The color-coded 
diagram on the HoverFly site indicating which channel 
from the Spektrum receiver plugged into the ports on the 
board wasn't immediately intuitive, but it eventually made 
sense. As I noted in Part 1, inserting and removing the 

various cables from the ESCs and receiver 
stresses the four metal-on-plastic anchors 
of the board. I managed to strip two of 
the connections during this part of the 
testing. Use tie wraps to secure the board 
until you're ready to fly. If you happen to 
strip the board, use 4-40 plastic bolts and 
nuts to lightly secure it in place. They're 
lightweight and strong. 

The translucent top shield (shown in 
the lead photo) is an important part of 
the overall design. Don't neglect it to save 
a few grams. If your copter lands head 
first in a field or if it starts to rain, you'll 
wish you had the shield in place. 



PHOTO 1 

HoverFly Open Board, 

wired for testing. 



Failsafe 



One of the worst things that can 
happen during flight is to lose the 
connection between the handheld R/C 
transmitter and the onboard receiver. 



SERVO 10.2012 




Whether due to interference, weak 
transmitter batteries, or accidently 
dropping the transmitter onto hard 
asphalt, without a transmitted 
signal your quadcopter is out of 
control. To prevent this, you need 
to define the failsafe control signals 
that the receiver should emit when 
the transmitter signal is lost. Every 
R/C manufacturer has a way of 
addressing the failsafe issue. 

In the Spektrum Sx6i system, 
failsafe options include throttle to 
off, throttle to idle, and hold on last 
command (that is, if in a turn, keep 
turning). The best choice for you 
depends on your environment. I 
prefer throttle to 'idle,' which 
hopefully results in a controlled 
crash. Throttle to 'off guarantees a 
hard crash, but minimizes chances 
that the copter will drift out of the 
flight area. 



PHOTO 2. Sky LiPo 4,400 mAh 
battery and iCharger 
with Para Board. 




Power 



For setup and testing, I used a laboratory grade 
switching power supply rated at 40V at 30A instead of a 
battery. The power supply enables me to monitor and 
precisely limit current during testing. I also don't like the 
idea of providing an untested quad with a self-contained 
power supply. I have the power supply cable tethered 
so that if the quad manages to move more than 
an inch above the testing table, the cable 
automatically disconnects and the quad comes 
to rest. 

For battery power — based on 
recommendations from Parallax support — 
I selected a three-cell, 11.1V, 4,400 mAh 
Li-Po (see Photo 2). The battery is rated 
at 30C continuous and 60C burst. The 
C rate is the rate at which a battery is 
discharged relative to its maximum 
capacity. A 1C rate is equivalent to 
discharging the entire battery 
capacity — 4,400 mAh — in one hour; 
30C means that the battery can 
discharge at a rate of 30 x 4,400 mAh, 
or 132A. Of course, the battery will be 
depleted in only two minutes. At the 60C burst 
level, the battery will deliver an amazing 264A. These 
are theoretical ratings — your mileage will vary. Still, you 
can see the need for short, low resistance connections 
between the battery and ESCs. Even a few tenths of an 
ohm can result in significant power loss. As a consequence 



of selecting Sky Li-Po over other comparable brands, I have 
to work with 4 mm bullet connectors. 

The next issue related to power is care and feeding of 
your Li-Po batteries. You need a good charger and power 
supply. I've had good luck with the iCharger 306B and 
matching ParaBoard (refer again to Photo 2). The charger 
is on the expensive side ($160), but with the ParaBoard 
(parallel charging board) I can charge four Li-Po batteries 
simultaneously. In other words, I can have a new set of 



PHOTO 3. Battery monitor with 

alarm showing "OK" status of a 

three-cell Li-Po battery. The 

two black objects on the left are 

ear-piercing alarms. 




SERVO 10.2012 71 




batteries in about an hour instead of half a day of 
connecting and disconnecting batteries from a single-cell 
charger. 

Another issue related to power is knowing when 
you're empty. Check out HobbyKing or Tower Hobbies for 
low voltage fingernail-sized alarm modules that sound off 
when battery voltage falls below a preset value. The best 
systems monitor the individual cells in the battery and 
sound an alarm when any of the three cells fall below 
critical voltage. Photo 3 shows one such system, 
available from HobbyKing ($3). Finally, although it might 
seem like a trivial matter, install plastic extenders on the Li- 
Po battery JST connectors, as in Photo 4. The extenders — 
which sell for about five cents each — will save your 
batteries from premature failure. Whenever you charge a 
Li-Po in a smart charger, you have to plug in the JST 
connector. Tugging on the wires to remove the plug is 
inevitable, and this will inevitably ruin the plug. 



Take Pictures 



At this point, take some pictures. If you've ever built 
and flown model rockets, planes, or copters, you know 
that the Elev-8 is going to show wear and tear, even if you 
manage to avoid an outright crash. Of course, your 
pictures should include more than simple camera shots. 
Include a "snapshot" of exactly where you're starting 
from, in terms of motor efficiency, battery output, and 
overall mechanical integrity. 

Create a logbook and catalog the actual KV, 
maximum rpm, and power draw from each of the four 
ESC motor circuits. You can expect these values to decay 
with normal wear and tear and the inevitable crashes. 
Fortunately, there is a variety of affordable meters on the 
market, starting with dedicated KV and rpm meters ($20, 
HobbyKing). For about twice that price, you can get a 
meter that also measures watts, battery internal 
resistance, and temperature, and that doubles as a servo 
tester. As you might expect, the 1,000 KV motors don't 



provide anywhere near the theoretical 1,000 x 1 1.1 or 
1 1,100 rpm at full throttle. Plus, the KV value will 
decrease as wear accumulates from improperly balanced 
propellers, impact, and the accumulation of dust and grit. 

Li-Po batteries also deteriorate with time and use. 
Track the internal resistance and pull a battery from 
service as soon as you notice a significant deviation 
from normal. You don't want a cell to fail in flight. 



Maintenance 



One of the best features of the Elev-8 is ease of 
maintenance. Given time and a workspace, everything is 
field-replaceable. With the Parallax Crash Kit, you're 
covered for motor mounts, motor parts, and props. You 
could even carry a spare aluminum tube, pre-drilled to 
accept the 4-40 mounting hardware. 

Post flight, you'll want to check the integrity of the top 
and bottom plates, and verify that the bolts are secure. If 
there's been a crash or one of the props grazed a bush or 
shrub, then remove the prop and check it with your 
balancing jig. Photo 5 shows my balancing station with an 
experimental 10" x 4.5" pitch prop. The prop is heavy on 
the right, meaning I'll have to sand off a bit of the training 
edge on that side of it. 

A related part of maintenance is checking the integrity 
of the four motors. As in Photo 6, make a habit of revving 
up your motors and looking at the collet at high speed. As 
in this figure, the outline is crisp with no evidence of 
wobbling. When the image of the collet starts to blur, it's 
time to rebalance the prop and/or rebuild the motor. 



Preflight 



As with a real copter, you should have and use a pre- 
flight checklist that includes battery check, prop collet 
check, transmitter battery check, and failsafe setting 
check. You'll also want to note the wind and weather 
forecast before you head out to the flight field. 



PHOTO 4. JST connector without (left) and with (right) protective sleeve. 
Recommended inexpensive insurance against JST connector failure from 
unplugging the connector by the wires. 



ve. 
)m 






The Fun Part 

Up to this point, it might seem 
like owning and maintaining a 
quadcopter is like owning a sailboat 
or an old house. You're always fixing 
something. However, that can be 
enjoyable. Of course, the real fun is 
experimenting with the craft. For 
example, on my to-do list is to work 
with the optional ultrasonic range 
finder and modify the flight 
computer so that instead of simply 
hovering at a given distance from 
the ground, the quadcopter takes 



72 SERVO 10.2012 



PHOTO 6. Side shot of a 
motor operating at high 
speed. Blur of the collet 
would indicate imbalance 
in the prop and/or 
motor. 



off and lands automatically. I'm also 
thinking of implementing a failsafe 
mode where the craft powers down to 
idle and then — as soon as the range 
finder registers an echo — hit the 
throttle to bring the craft down as 
softly as possible. 

With multiple channels, lots of 
space, and an onboard carrying 
capacity of two pounds, you're limited 
by your budget and imagination. The 
GoPro HD Hero2 video camera ($300) is 
especially popular among quadcopter 
enthusiasts, as are the inexpensive ($40) 
dice mini cameras with night vision. I 
have my eye on a remote telemetry 
system that lets me monitor battery and 
motor conditions in real time. For now, 
I'm using an iPod with iChat for Wi-Fi 
based real time video. 

Part of the fun of working with the Elev-8 is 
discovering what's possible. Spend some time on the R/C 
supply sites including HobbyKing, Tower Hobbies, and 
Xheli, and you'll no doubt discover technologies that you 
didn't know existed. If you have the patience to wait for 
overseas delivery, HobbyKing offers amazing discounts and 
a huge selection. If you need supplies tomorrow, then 
Tower Hobbies is worth considering. Of course, Parallax 
stocks spare motors and parts for the Elev-8. 




Closing Thoughts 



This fun and (in my opinion) easy to build kit probably 
shouldn't be your introduction to 
robotic R/C flight. Think about it. As a 
robotics enthusiast, you already need 
to know electronics, computers, and at 
least rudimentary mechanical 
engineering. Now, you've added another 
dimension — it's like having the scientists that 
developed the space shuttle suit up and take over 
the role of astronaut. It's possible, but not overnight. 

You'll need to find a local R/C enthusiast to show you 
the ropes — from where it's safe to fly to how to judge 
wind speed and direction (there's an app for that). You 
might consider a short training tether of 1" diameter rope, 
with one end affixed to the bottom plate of the Elev-8 and 
the other free. Because the load increases as the craft 
rises, the craft can't shoot up and crash on to a rooftop 
before you manage to hit the power switch on your 
transmitter. Make sure the rope is dense enough to stay 
put with the full force of the motors pushing the Elev-8 
upward. If you haven't touched an R/C transmitter in 
years, then go to Amazon and buy a Syma S107 R/C 
helicopter in the color of your choice for $20. Fly figure 8s 



in front of you, overhead, in front of active air 
conditioners, and at night with the lights out. Don't even 
think about powering up the Elev-8 until you can take off, 
fly, and land the Syma flawlessly. 

Then, consider a simulator add-on for your R/C 
transmitter, such as the RealFlight R/C flight simulator. 
These simulator packages contain a standard cable for 
your R/C transmitter and software for your PC. Select the 
simplest single-engine helicopter model and start flying. 
The advantage of this system is that you get used to the 
same transmitter interface you'll be using on the Elev-8. 
The disadvantage is that there are no Elev-8 models to fly 
— you'll have to make do with a helicopter. 

Still, you'll get a feel for the transmitter controls, and 
this newfound dexterity will apply directly to your control 
of the Elev-8. Happy flying! SV 



PHOTO 5. Balancing props after 

a crash is mandatory. This 

balancing tool uses miniature 

bearings. More sensitive tools 

use magnetic suspension. 




SERVO 10.2012 73 





ru 




The Many Ways to Control a Robot 



b y 



m 



I I 



I had an interesting conversation with a friend about some of my recent columns, in 
particular, we talked about ways to control robots other than visual sensors such as the 
Kinect and verbal control via speech recognition. We discussed early robots that used crude 
wireless or wired control, as well as more modern concepts such as NASA's one ton Curiosity 
that is being controlled from Earth all the way to Mars — despite the 10 to 15 minute signal 
delays. These rovers require a lot of autonomy because of these signal delays, but remote 
control capability of some functions is also a must. 

As designers and builders of our robotic creations, we still want some sort of control over 
our machines, even if the basic control is through autonomous sensor interaction with the 
outside world. Quite frankly, there are many ways that allow a human to control a robot 
outside of programming an autonomous bot. I won't be discussing internal robot control 
methods (such as a sensor controlling movements). I am going to concentrate on strictly 
'hands-on' human control methods and steer away from total autonomy. 



Robots have fascinated me since I 
was a kid and first read / Robot by 
Isaac Asimov. In June 1956, the Boy 
Scout magazine, Boys' Life had an 
article entitled Gismo and I, by 
Sherwood Fuehrer. Gismo the Great — 
shown in Figure 1 — was human 
sized and was 'so neat' in my young 
mind. Fuehrer had used parts that he 
got from his dad, an engineer, and 
other scrounged parts. He used an old 
tool box as the control panel. It had 
no autonomy other than what switch 
its young inventor pushed or flipped. 
(You can see his 'control box' sitting 
on a stool.) 

I collected a pile of parts to build 
my own 'Cosmo' that was mostly 
heavy plywood, furnace ducting, juke 
box parts and motors, a heavy tape 
recorder, and assorted light bulbs. I 
tried to make it move on some toy 
rubber tires and two juke box motors, 

74 SERVO 10.2012 




FIGURE 1. Original Gismo the Great 
from 1956 Boys' Life. 



but the heavy beast fell over once and 
shook our whole house. (Tall robots 
don't stand for long when the builder 
uses single speed motors for the drive 
wheels.) After that, I just kept it 
stationary with a recorded voice and 
flashing lights. The controls for all the 
lights, motors, relays, and tape 
recorder were what interested me the 
most. It was nowhere as cool as 
Gismo in Boys Life, but it kept me 
busy. 

Years later in 1986, as a scout 
master and robotics engineer at 
Rockwell, I was asked by Boys' Life to 
design and write about a simple, but 
more modern robot that scouts could 
build on their own, and to keep the 
total cost below $50. The editor at 
Boys' Life decided to name it 
'Gismo2BL' as the "son of Gismo" 
from the earlier article. I used a typical 
plastic waste basket as the body, 



www.servomagazine.com/index.php7/magazine/article/october2012_ThenNow 



plastic pipe for the arms, and two 
dual 6 VDC motors to power the arms 
and wheels. Figure 2 shows the basic 
layout of the robot and a simple 
schematic from the February 1987 
article. 

I had to avoid the use of a 
68HC1 1 microcontroller (or similar 
microcontroller of that era) to keep 
the cost down and for simplicity. 
Control was by two sets of 
momentary DPDT switches from 
RadioShack for the two arms and the 
two wheels. I felt I should use 
flattened 'tin can' metal for the wheel 
mounts since few kids had the 
machine shop shears and metal stock 
that I had available in my garage. My 
twin sons, Jimmy and Tommy, who 
were scouts at the time were my test 
subjects to verify that a kid could 
make the robot from scratch. Herbach 
and Rademan — the surplus house in 
Philadelphia — was the source for the 
$4.95 dual motors. They had to 
temporarily add more staff and 
actually manufacture more of the 
motors as 27,000 kids built or tried to 
build the robot. 

Switches — the Most 
Basic Control System 

Simple switch control is used in 
many toys and toy robots, as well as 
in most power tools, industrial 
machines, and appliances. I remember 
one toy Jeep that I had that used a 
two-button wired remote control: one 
button each for forward and reverse, 
with the front wheels mechanically 
steering to the right in reverse. To 
change direction, you had to back up 
as far as it took to face the new 
direction that you wanted to go; the 
wheels were straight for 'forward.' 
Crude, but it worked. It was just a 
simple on-off type of control. Add in 
polarity reversal for battery-powered 
tools and variable speed control, and 
you still have on-off switch control. To 
manipulate something in this manner 
from a remote location, one usually 
has to use wires from two to as many 
as hundreds, depending on the 
number of controlled functions. 



FIGURE 2. Simple control schematic for Boys' Life 1987 Gismo2BL robot. 

Robot Assemble 




SWLTCK DETAIL 



Robots with many functions can 
operate remarkably well with switch 
control. Add in variable speed and 
polarity reversal, and you can control 
almost anything. Pilots of small 
underwater ROVs (remotely-operated 
vehicles) using a cable to the surface 
can not only control various thrusters, 
lights, and robotic arms, but they 
literally control all parts and 
subsystems of the vessel. A variable 
speed multi-axis joystick works the 
best for a robotic arm, though. With 
TV feedback, pilots can literally feel as 
if they are right there in the water. 

This is just one example of how 
the simplest of control systems can 
apply to the most complex machine. 
Certainly, the more complex of these 
research robots have many computers 
and microcontroller systems, but 
switched controls are prevalent in 
everything from police and military 



robots, boats, cars, and even aircraft 
and spacecraft. 

Cutting the Cord 
With Remote Control 

Many of us eventually want to 
have our robots autonomously find 
their way around a shop or house, but 
autonomy is not necessarily a function 
of all robots — despite what purists 
may say. When it comes to a human 
controlling a robot, the first thing any 
experimenter wants to do with a 
machine that has a cord for control 
and/or power is to sever that cord. I 
have seen other people's robot 
projects, and have tried many 
methods myself of 'cutting the cord' 
in robot control. 

One of the most popular methods 
for any type of technical experimenter 
is to use methods and parts from toys 

SERVO 10.2012 75 



Discuss this article in the SERVO Magazine forums at http://forum.servomagazine.com 




FIGURE 3. 
Panasonic 38 kHz 
infrared receiver. 



— especially low cost walkie-talkies. 
They are cheap — sometimes too 
cheap — easily obtainable, and easily 
hackable. 

Refining RF and 
IR Remote Control 
Methods 

Cordless remote control can be 
accomplished via an RF (radio 
frequency) link, an IR (infrared) beam, 
or by an ultrasonic signal. The latter 
was used for remote control of TVs 
several decades ago, but lost out to 
today's IR remote controls. IR control 
works well for television and various 
audio systems that require only a 
single control function at a time. 

I have seen so many ways that 
people have used to get controlling 
signals from a handheld device to 
their robot. Experimenters have used 
DTMF telephone key pads to send 10 
or 12 different dual-tone 'codes' via a 
walkie-talkie to a walkie-talkie placed 
within the robot with a DTMF decoder 
attached. Unfortunately, most of 
these ended up as on-off control only. 

One could have a button 
depressed that closed a circuit in the 
robot, as long as the button remained 
depressed. Or, it could be a toggle 
on/toggle off proposition with the 
button depressed once to start, and 
then again to stop. Surplus houses 
had IR decoders for TVs — not just the 
little receiver cubes — that were 

76 SERVO 10.2012 



hacked to receive an RF signal sent 
via a TV remote control that was 
also hacked to send an RF signal. 
There were so many versions that I 
saw in the 70s and '80s. 

Many robot experimenters 
have used surplus handheld IR TV 
remote controls for their robots. 
Simple IR receivers such as the 
Panasonic module from Parallax 
(shown in Figure 3) are available 
for just a few dollars. The coded 
signals can be received, decoded 
by a microcontroller, and used to 
b control many functions on a robot. 
Most use a 38 kHz carrier 
frequency and are easily converted 
to small robot controllers. 
For example, the volume or DVD 
player arrows on a controller can be 
used for forward and reverse on a 
robot, and the remaining buttons can 
be used for controlling other 
functions. An experimenter can view 
the output of the remote on an 
inexpensive IR receiver module and 
view it on an oscilloscope or 
computer. They copy and reproduce 
the code pulses, and then program 
their microcontroller to recognize each 
signal as a particular robot command. 

There really is no limit 
to the methods that can 
be used to control a 
computer, or even 
a robot 

I know of several experimenters who 
gutted a TV remote control and 
hardwired wires from the copper 
traces beneath the rubber buttons, 
then ran them to a more conventional 
keypad. They didn't like the TV-specific 
wording on the remote and fashioned 
a keypad more to their liking, while 
still using the remote's electronics. 

IR control is cheap and reliable, 
but it does have drawbacks. Outdoors, 
IR is subject to interference by 
sunlight. Basically, the IR signal is lost 



due to being overpowered by the sun, 
though a lot of experimental robots 
are used indoors in subdued lighting. 
Because of these types of factors and 
limitations, most remote control of a 
robot is accomplished via an RF radio 
link which has a much longer range, 
no problems with the sun or walls, 
and large bandwidth. 

Early Model 
Radio Control 

Let's face it. The first real radio 
control for hobbyists was for model 
airplanes and boats. When airplane 
modelers got tired of spinning in a 
circle while holding onto a pair of 
control lines that led to the speeding 
model, they began to think about 
radio control. The same went for 
model power boat builders who 
watched their boats heading for the 
opposite shore of a lake. There had to 
be a better way. There was. Radio 
control. 

Before World War II, there was 
little available to construct small and 
affordable radio systems that included 
the transmitter and receiver. Radio 
tubes were large, and drew a lot of 
power for the filament and the high 
voltages required. After the war, 
surplus electronic equipment became 
available to civilians, and some good 
(but still bulky) radio control 
equipment was being built for model 
control. 

One of the more successful 
commercially-available systems was 
the tuned reed receiver. It was 
essentially an electromechanical device 
consisting of a series of resonate 
reeds that would respond to a 
transmitted signal of the particular 
audible frequency. The resonating 
reed would vibrate a set of contacts 
enough to allow a current to pass 
through and close an appropriate 
relay, and thus control a specific 
function. These systems were used 
from the 1950s to the early 1970s 
when transistorized equipment 
became readily available to all. 

Another system used a single 
button transmitter and what was 



Tom Carroll can be reached at TWCarroll@aol.com. 



known as an 'escapement relay' 
connected to a receiver in a model 
plane. When the button on the 
transmitter was depressed, the 
signal caused the escapement to 
move, say, 90 degrees to the right, 
and move the plane's rudder fully 
to the right. Another push of the 
button would cause the 
escapement to move the rudder 
back to center. Another push 
moved the left rudder, and another 
push brought it back to center. The 
escapement motion was powered 
by a wound-up rubber band the 
length of the fuselage's interior. 
Figure 4 is a display of four early 
1960's rubber-band powered 
escapement control systems from 
www.mccrash-racing.co.uk. 

Radio Control 
Systems Incorporate 
Servos 

Jumping ahead several decades, it 
is quite clear that radio control 
systems have dramatically improved. 
The main improvement has been 
proportional control. Instead of the 
'bang-bang' one way or via another 
type of control, movements can be 
slight and at any speed or direction 
that the operator desires. This is the 
same type of physical movement that 
you would find in a real airplane, car, 
or robot. This proportional movement 
is accomplished by servos: small gear 
motors with an attached 
potentiometer that feed positions 
back to an internal circuit board that 
responds to a received series of 
pulses. It was servos that not only 
allowed remote control of many 
movements, but these small and 
inexpensive devices became the main 
method to provide numerous motions 
to experimenter's robots. 

When I first started to use radio 
control for robot movie props (such as 
for the 1984 film, "Revenge of the 
Nerds"), I used Futaba radios 
operating at 75 MHz since the 72 
MHz band was limited to airborne use 
only. Movie prop and promotional 
robots really had size requirements 




FIGURE 4. Early super-regen receiver rubber-band escapement demos. 



just the opposite of flying models. 
Airplanes needed the lightest and, 
therefore, the smallest receivers 
possible. 

Large robots — especially 
promotional ones — could get by with 
any size receiver, however, the very 
smallest transmitters were used so 
that the operation of the robot could 
be hidden. Vantec supplied virtually all 
of the modified systems that I used 



FIGURE 5. Hitec 7 
Eclipse Pro. 




for the props. Larger robots such as 
action props required large motors 
and proportionally higher current 
speed controllers. 

'Feedback' was achieved by 
human vision. The operator controlled 
speed, direction, and arm motions by 
looking at the robot as it moved 
around a movie set or amongst a 
crowd of people at a convention. To 
satisfy one of my customer's needs for 
a concealed transmitter for his 
promotional bot, I built the 
transmitter into a gutted 35 mm 
camera with a joystick and control 
buttons on the back of the camera, 
out of sight. The actual transmitter 
was in a small camera bag with 
multiple wires from the joystick and 
slide pots running into the camera 
bag transmitter. 

A wireless microphone was also in 
the back of the camera. I could stand 
off to the side with the camera at my 
waist and easily control the robot. 
When the bot needed to speak, I 
would raise the camera to my face, 
pretending to take a photo, and speak 
through the mic. The attached flash 
worked to assist in the illusion. 

The new transmitters and 
receivers for today's radio control have 
features too numerous to list. The 
Hitec 7 Eclipse Pro shown in Figure 5 

SERVO 10.2012 77 



FIGURE 6. 
Hitec Optic 6 
Sport. 



wt.o 



is one of this latest breed of R/C 
transmitters. The 72-75 MHz bands 
have lost favor to the new 2.4 GHz 
spread-spectrum systems. The more 
affordable Hitec Optic 6 Sport shown 
in Figure 6 is a six-channel spread- 
spectrum system that has been used 
on many combat robots. The extra 
channels provide control through two 
joysticks for the wheel drives and a 
weapon system, with spares for firing 
the weapon. With microprocessor 



FIGURE 7. Futaba 4PKS 
2.4 GHz spread-spectrum 
transmitter. 




control and informative LCD displays, 
there are so many functions and 
capabilities available in high-end 
transmitters. Most are applicable to 
model airplane and helicopter flying, 
but are also programmable to help 
make combat robots easier to 
control. 

Radio Control 
Transmitter 
Configurations 

Commercial radio 
control manufacturers 
designed two very different 
transmitter configurations 
for aircraft and for ground- 
based cars. The rectangular 
two-joystick configuration 
(shown back in Figure 4) has 
become the favorite for remote robot 
control due to the availability for more 
control channels. Combat robots have 
more functions needed other than just 
two differentially-driven wheels. 
Combatants need to control various 
weapons with possible requirements 
for unique movements. Some robots 
need to reverse wheel driving 
direction if they get flipped over in 
a bout. 

The gun-style transmitter shown 
in Figure 7 is a favorite with model 
race car drivers since it allows easy 
and quick direction control of the car's 
two front wheels in a race, with a 



FIGURE 8. ZigBee 
PRO S2B 63 mW 
wire antenna. 




trigger controlling the car's speed. The 
thumb can be used to fire/trigger a 
weapon for a combat robot. However, 
most robots do not use the 
Ackermann-style steering that is used 
in race cars, but instead use 
differential steering. 

Differential steering guides the 
robot by controlling the speed and 
direction of the right and left drive 
wheels. The gun-style transmitters 
don't have as many channels as the 
dual joystick transmitters have. Many 
non-combat robots require even more 
channels than their battling cousins — 
especially those that might have a 
complex arm and/or claw attached. 

Model R/C control systems will 
continue to dominate combat robots, 
as well as many other experimental 
robots that are not under total 
autonomous control. 

ZigBee and XBee 
for Robots 

XBee has become a popular robot 
communications and control system 
used by many robot builders. Many 
confuse ZigBee and XBee. ZigBee is a 
specification for a suite of high-level 
communication protocols using small, 
low power digital radios based on an 
IEEE 802.14.4 standard for personal 
area networks. XBee is the name of a 
product made by the Digi 
Corporation. Digi manufactures over 
70 different varieties of XBee modules 
with different antennas, power levels, 
and capabilities. ZigBee remote 
control has found favor with some 
robot experimenters, mainly because 
of its low power consumption. 

ZigBee devices are often used in 
mesh network form to transmit data 
over long distances, passing data 
through intermediate devices to reach 
more distant ones. This allows ZigBee 
networks to be formed ad-hoc, with 
no centralized control or high power 
transmitter/receiver able to reach all 
of the devices. ZigBee is targeted at 
applications that require a low data 
rate (250 kbit/s), long battery life, and 
secure networking. 

ZigBee is suited for periodic or 



78 SERVO 10.2012 







FIGURE 9. XStick ZB AT 
(AT command 
mode ready). 



FIGURE 10. XBee 
serial communication 
with an Ardunio. 




intermittent data, or a single signal 
transmission from a sensor or input 
device. Applications include simple 
two-way robot control, traffic 
management systems, and other 
consumer and industrial equipment 
that requires short-range wireless 
transfer of data at relatively low rates. 
The technology defined by the ZigBee 
specification is intended to be simpler 
and less expensive than other WPANs, 
such as Bluetooth. 

ZigBee operates in the industrial, 
scientific, and medical (ISM) radio 
bands of 915 MHz in the USA and 
Australia, and 2.4 GHz in most other 
areas worldwide. Data transmission 
rates vary from 20 to 900 
kilobits/second. I recently 
received some XBee S2B Pro 
modules ("Figure 8) and I 
quickly hooked them up for a 
test. I was communicating with 
the XStick ZB AT USB dongle 
(shown in Figure 9) on my 
laptop. I was hoping for a bit 
more range, but the dongle is 
low power — just a bit over 2 
mW — and I had a bit of 
trouble with longer range due 
to the small, internal antenna. 

I used an old spectrum 
analyzer to look at the 2.4 GHz 
signal, but it was gone by the 
time I brought the wireless test 
board with the XBee module 
attached down to my garage. 
The dongle receiver does have 



a sensitivity of -90 dBm — not too bad 
for such a small device. 

The XBee module with a wire 
antenna has a 63 mW output, and 
should be able to transmit a mile or 
more outdoors and several hundred 
feet indoors. However, to transmit in 
both directions with the greater 
range, both 'ends' must have the 
higher 63 mW output. Not just one. 

When mounting the module, be 
sure to have the antenna pointing 
straight up and not blocked by any 
conductive covering. The XBee 
module has a baud rate of up to 1 
Mbps and the dongle has 250 Kbps. 
Figure 10 shows an XBee/Arduino 
setup with an interconnecting logic 




FIGURE 11. GT3D device can control a computer 
or robot through eye commands. 



level converter from the Bildr.org 

blog site. I have seen these used on 
RoboMagellan entries and many other 
types where experimenters needed 
data exchange for their operations. 

Final Thoughts 

There are many more varieties of 
RF and control links that have been 
used by robot experimenters. Wi-Fi 
(that uses the IEEE 802.1 1 standard) 
has been used for robot control, 
though we mostly use this RF 
technology for a close proximity PC 
network. It has its security problems, 
but is fine for robot use. Bluetooth — 
operating in the 2.4 to 2.48 GHz band 
— is another control link 
technology that has been used 
for robot control. Bluetooth is 
a packet-based protocol with a 
master-slave structure using 
frequency-hopping spread- 
spectrum technology. 

There really is no limit to 
the methods that can be used 
to control a computer, or even 
a robot. Figure 11 shows a 
computer application that 
can easily be converted to 
robot control. These glasses 
developed at the Imperial 
College in England allow 
a disabled person to control 
a computer with just their 
eyes. Just think of the 
possibilities! 

SERVO 10.2012 79 




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